Settings UI: Fix spelling error and make spell checker happy (#41403)

## Summary of the Pull Request

- Renames `NavigatablePage` to `NavigablePage` to fix a spelling error.
- Reverts related entries in `exclude.txt` that triggered a forbidden
pattern error in the spell checker.
- The spell checker does not allow PascalCase words like
`NavigatablePage` in `exclude.txt` because of its automatic casing
rules.

 
Regression: #41285

---------

Co-authored-by: vanzue <vanzue@outlook.com>

src/settings-ui/Settings.UI/SettingsXAML/Views/PowerLauncherPage.xaml

@@ -1,4 +1,4 @@
-<local:NavigatablePage
+<local:NavigablePage
     x:Class="Microsoft.PowerToys.Settings.UI.Views.PowerLauncherPage"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
@@ -15,7 +15,7 @@
     AutomationProperties.LandmarkType="Main"
     mc:Ignorable="d">
 
-    <local:NavigatablePage.Resources>
+    <local:NavigablePage.Resources>
         <Style x:Key="OptionSeparator" TargetType="Rectangle">
             <Setter Property="Height" Value="1" />
             <Setter Property="HorizontalAlignment" Value="Stretch" />
@@ -304,7 +304,7 @@
         <DataTemplate x:Key="EmptyTemplate" x:DataType="viewModels:PluginAdditionalOptionViewModel">
             <StackPanel HorizontalAlignment="Stretch" Orientation="Vertical" />
         </DataTemplate>
-    </local:NavigatablePage.Resources>
+    </local:NavigablePage.Resources>
 
     <controls:SettingsPageControl x:Uid="PowerLauncher" ModuleImageSource="ms-appx:///Assets/Settings/Modules/Run.png">
         <controls:SettingsPageControl.ModuleContent>
@@ -816,4 +816,4 @@
             <controls:PageLink Link="https://github.com/betsegaw/windowwalker/" Text="Beta Tadele's Window Walker" />
         </controls:SettingsPageControl.SecondaryLinks>
     </controls:SettingsPageControl>
-</local:NavigatablePage>
+</local:NavigablePage>