Removing WCT 7.x references (#41733)

## Summary of the Pull Request

This PR introduces the following changes:
- Replace the MarkdownTextBlock with the latest version in
CommunityToolkit Labs, and removing the 7.x version.
- Replacing WrapPanel from 7.x with the 8.0 version.
- Replacing converters from 7.x with the 8.0 version.
- Remove unused namespaces related to the Toolkit

No visual or behavior changes, except for the release notes that now
look better :):

Before:
<img width="678" height="906" alt="image"
src="https://github.com/user-attachments/assets/8b3ac267-b4cd-499c-8e16-d8420a176a4a"
/>


After:
<img width="846" height="881" alt="image"
src="https://github.com/user-attachments/assets/cb4f2d85-0c23-4263-80d6-28c2ab403704"
/>


<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

---------

Co-authored-by: Gordon Lam <73506701+yeelam-gordon@users.noreply.github.com>
Co-authored-by: Gordon Lam (SH) <yeelam@microsoft.com>

src/settings-ui/Settings.UI/SettingsXAML/Controls/ColorFormatEditor.xaml

@@ -9,7 +9,7 @@
     xmlns:converters="using:Microsoft.PowerToys.Settings.UI.Converters"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:tk7controls="using:CommunityToolkit.WinUI.UI.Controls"
+    xmlns:tkcontrols="using:CommunityToolkit.WinUI.Controls"
     mc:Ignorable="d">
     <UserControl.Resources>
         <converters:ColorFormatConverter x:Key="ColorFormatConverter" />
@@ -61,7 +61,7 @@
         </DataTemplate>
 
         <ItemsPanelTemplate x:Key="ItemPanelTemplate">
-            <tk7controls:WrapPanel
+            <tkcontrols:WrapPanel
                 HorizontalSpacing="20"
                 Orientation="Horizontal"
                 VerticalSpacing="4" />

src/settings-ui/Settings.UI/SettingsXAML/Controls/PowerAccentShortcutControl.xaml

@@ -5,7 +5,7 @@
     xmlns:controls="using:Microsoft.PowerToys.Settings.UI.Controls"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:tk7controls="using:CommunityToolkit.WinUI.UI.Controls"
+    xmlns:tkcontrols="using:CommunityToolkit.WinUI.Controls"
     d:DesignHeight="300"
     d:DesignWidth="400"
     mc:Ignorable="d">
@@ -35,7 +35,7 @@
                 </DataTemplate>
             </ItemsControl.ItemTemplate>
         </ItemsControl>
-        <tk7controls:MarkdownTextBlock
+        <tkcontrols:MarkdownTextBlock
             Grid.Column="1"
             Margin="8,0,0,0"
             VerticalAlignment="Center"

src/settings-ui/Settings.UI/SettingsXAML/Controls/SettingsPageControl/SettingsPageControl.xaml

@@ -6,7 +6,7 @@
     xmlns:converters="using:Microsoft.PowerToys.Settings.UI.Converters"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:tk7controls="using:CommunityToolkit.WinUI.UI.Controls"
+    xmlns:tkcontrols="using:CommunityToolkit.WinUI.Controls"
     Loaded="UserControl_Loaded"
     mc:Ignorable="d">
     <UserControl.Resources>
@@ -81,7 +81,7 @@
                             </ItemsControl.ItemTemplate>
                             <ItemsControl.ItemsPanel>
                                 <ItemsPanelTemplate>
-                                    <tk7controls:WrapPanel HorizontalSpacing="24" Orientation="Horizontal" />
+                                    <tkcontrols:WrapPanel HorizontalSpacing="24" Orientation="Horizontal" />
                                 </ItemsPanelTemplate>
                             </ItemsControl.ItemsPanel>
                         </ItemsControl>
@@ -123,7 +123,7 @@
                         </ItemsControl.ItemTemplate>
                         <ItemsControl.ItemsPanel>
                             <ItemsPanelTemplate>
-                                <tk7controls:WrapPanel HorizontalSpacing="24" Orientation="Horizontal" />
+                                <tkcontrols:WrapPanel HorizontalSpacing="24" Orientation="Horizontal" />
                             </ItemsPanelTemplate>
                         </ItemsControl.ItemsPanel>
                     </ItemsControl>

src/settings-ui/Settings.UI/SettingsXAML/Controls/ShortcutControl/ShortcutDialogContentControl.xaml

@@ -5,7 +5,7 @@
     xmlns:controls="using:Microsoft.PowerToys.Settings.UI.Controls"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:tk7controls="using:CommunityToolkit.WinUI.UI.Controls"
+    xmlns:tkcontrols="using:CommunityToolkit.WinUI.Controls"
     x:Name="ShortcutContentControl"
     mc:Ignorable="d">
     <Grid MinWidth="498" MinHeight="220">
@@ -71,9 +71,8 @@
                     Message="{Binding ElementName=ShortcutContentControl, Path=ConflictMessage, Mode=OneWay}"
                     Severity="Warning" />
             </Grid>
-            <tk7controls:MarkdownTextBlock
+            <tkcontrols:MarkdownTextBlock
                 x:Uid="InvalidShortcutWarningLabel"
-                Background="Transparent"
                 FontSize="12"
                 Foreground="{ThemeResource TextFillColorSecondaryBrush}" />
         </StackPanel>

src/settings-ui/Settings.UI/SettingsXAML/Controls/ShortcutControl/ShortcutWithTextLabelControl.xaml

@@ -5,7 +5,7 @@
     xmlns:controls="using:Microsoft.PowerToys.Settings.UI.Controls"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-    xmlns:tk7controls="using:CommunityToolkit.WinUI.UI.Controls"
+    xmlns:tkcontrols="using:CommunityToolkit.WinUI.Controls"
     d:DesignHeight="300"
     d:DesignWidth="400"
     mc:Ignorable="d">
@@ -38,11 +38,10 @@
                 </DataTemplate>
             </ItemsControl.ItemTemplate>
         </ItemsControl>
-        <tk7controls:MarkdownTextBlock
+        <tkcontrols:MarkdownTextBlock
             x:Name="LabelControl"
             Grid.Column="1"
             VerticalAlignment="Center"
-            Background="Transparent"
             Text="{x:Bind Text}" />
         <VisualStateManager.VisualStateGroups>
             <VisualStateGroup x:Name="LabelPlacementStates">