[MouseHighlighter]Add always-on pointer (#27186)

* [MouseHighlighter]Add always pointer

Make color pick UI ARGB
Delete Opacity setting

* Fix opacity and color

Fix "always color" incorrectly initialized
Revert default opacity to 65%, which was unintentionally lowered to 25% when
changing to percent

* Fix crash when opening MouseUtils settings page

Migration code was bugged, made malformed json and led to settings page crash.

* Implement migration in module side

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

@@ -0,0 +1,42 @@
+<UserControl
+    x:Class="Microsoft.PowerToys.Settings.UI.Controls.AlphaColorPickerButton"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:local="using:Microsoft.PowerToys.Settings.UI.Controls"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    d:DesignHeight="300"
+    d:DesignWidth="400"
+    mc:Ignorable="d">
+
+    <Grid>
+        <!--TODO(stefan): ToDisplayName is no longer available in ColorHelper
+        <DropDownButton Padding="4,4,8,4" AutomationProperties.FullDescription="{x:Bind clr:ColorHelper.ToDisplayName(SelectedColor), Mode=OneWay }">
+        -->
+        <DropDownButton Padding="4,4,8,4">
+            <Border
+                x:Name="ColorPreviewBorder"
+                Width="48"
+                Height="24"
+                BorderBrush="{ThemeResource CardStrokeColorDefaultBrush}"
+                BorderThickness="1"
+                CornerRadius="{ThemeResource ControlCornerRadius}">
+                <Border.Background>
+                    <SolidColorBrush Color="{x:Bind SelectedColor, Mode=OneWay}" />
+                </Border.Background>
+            </Border>
+            <DropDownButton.Flyout>
+                <Flyout>
+                    <ColorPicker
+                        IsAlphaEnabled="True"
+                        IsAlphaSliderVisible="True"
+                        IsAlphaTextInputVisible="True"
+                        IsColorChannelTextInputVisible="True"
+                        IsColorSliderVisible="True"
+                        IsHexInputVisible="True"
+                        Color="{x:Bind SelectedColor, Mode=TwoWay}" />
+                </Flyout>
+            </DropDownButton.Flyout>
+        </DropDownButton>
+    </Grid>
+</UserControl>

src/settings-ui/Settings.UI/SettingsXAML/Controls/AlphaColorPickerButton.xaml.cs

@@ -0,0 +1,59 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Windows.UI;
+
+namespace Microsoft.PowerToys.Settings.UI.Controls
+{
+    public sealed partial class AlphaColorPickerButton : UserControl
+    {
+        private Color _selectedColor;
+
+        public Color SelectedColor
+        {
+            get
+            {
+                return _selectedColor;
+            }
+
+            set
+            {
+                if (_selectedColor != value)
+                {
+                    _selectedColor = value;
+                    SetValue(SelectedColorProperty, value);
+                }
+            }
+        }
+
+        public static readonly DependencyProperty SelectedColorProperty = DependencyProperty.Register("SelectedColor", typeof(Color), typeof(AlphaColorPickerButton), new PropertyMetadata(null));
+
+        public AlphaColorPickerButton()
+        {
+            this.InitializeComponent();
+            IsEnabledChanged -= AlphaColorPickerButton_IsEnabledChanged;
+            SetEnabledState();
+            IsEnabledChanged += AlphaColorPickerButton_IsEnabledChanged;
+        }
+
+        private void AlphaColorPickerButton_IsEnabledChanged(object sender, DependencyPropertyChangedEventArgs e)
+        {
+            SetEnabledState();
+        }
+
+        private void SetEnabledState()
+        {
+            if (this.IsEnabled)
+            {
+                ColorPreviewBorder.Opacity = 1;
+            }
+            else
+            {
+                ColorPreviewBorder.Opacity = 0.2;
+            }
+        }
+    }
+}