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/DashboardPage.xaml

@@ -1,4 +1,4 @@
-<local:NavigatablePage
+<local:NavigablePage
     x:Class="Microsoft.PowerToys.Settings.UI.Views.DashboardPage"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
@@ -14,7 +14,7 @@
     AutomationProperties.LandmarkType="Main"
     DataContext="DashboardViewModel"
     mc:Ignorable="d">
-    <local:NavigatablePage.Resources>
+    <local:NavigablePage.Resources>
         <converters:ModuleItemTemplateSelector
             x:Key="ModuleItemTemplateSelector"
             ActivationTemplate="{StaticResource ModuleItemActivationTemplate}"
@@ -74,7 +74,7 @@
                     TextWrapping="WrapWholeWords" />
             </Grid>
         </DataTemplate>
-    </local:NavigatablePage.Resources>
+    </local:NavigablePage.Resources>
     <Grid Margin="16,0,0,0" RowSpacing="12">
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto" />
@@ -363,4 +363,4 @@
             </VisualStateGroup>
         </VisualStateManager.VisualStateGroups>
     </Grid>
-</local:NavigatablePage>
+</local:NavigablePage>