[CmdPal] Introduce Small, Medium, and Large sizing options for Details (#43956)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request
This PR introduces 3 new sizing options to the Details Panel in the
Extensions API.
- `Small` (Default)
- `Medium`
- `Large`
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## PR Checklist

- [x] Closes: #43251
<!-- - [ ] Closes: #yyy (add separate lines for additional resolved
issues) -->
- [ ] **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

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

Here's how it looks like:
```csharp
new ListItem(new NoOpCommand())
{
    Title = "Details on ListItems (Medium)",
    Details = new Details()
    {
        Title = "This item has medium details size",
        Body = "Each of these items can have a `Body` formatted with **Markdown**",
        Size = ContentSize.Medium,
    },
},
```

### Moving Pictures


![DetailsSize](https://github.com/user-attachments/assets/ae11b767-ecba-4b39-bd81-3e77eec93ed0)


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

src/modules/cmdpal/Microsoft.CmdPal.UI/Converters/DetailsSizeToGridLengthConverter.cs

@@ -0,0 +1,39 @@
+// 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.CommandPalette.Extensions;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Data;
+
+namespace Microsoft.CmdPal.UI;
+
+public partial class DetailsSizeToGridLengthConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, string language)
+    {
+        if (value is ContentSize size)
+        {
+            // This converter calculates the Star width for the LIST.
+            //
+            // The input 'size' (ContentSize) represents the TARGET WIDTH desired for the DETAILS PANEL.
+            //
+            // To ensure the Details Panel achieves its target size (e.g. ContentSize.Large),
+            // we must shrink the List and let the Details fill the available space.
+            // (e.g., A larger target size for Details results in a smaller Star value for the List).
+            var starValue = size switch
+            {
+                ContentSize.Small => 3.0,
+                ContentSize.Medium => 2.0,
+                ContentSize.Large => 1.0,
+                _ => 3.0,
+            };
+
+            return new GridLength(starValue, GridUnitType.Star);
+        }
+
+        return new GridLength(3.0, GridUnitType.Star);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, string language) => throw new NotImplementedException();
+}

src/modules/cmdpal/Microsoft.CmdPal.UI/Pages/ShellPage.xaml

@@ -26,6 +26,7 @@
                 EmptyValue="Collapsed"
                 NotEmptyValue="Visible" />
 
+            <cmdpalUI:DetailsSizeToGridLengthConverter x:Key="SizeToWidthConverter" />
             <cmdpalUI:MessageStateToSeverityConverter x:Key="MessageStateToSeverityConverter" />
 
             <cmdpalUI:DetailsDataTemplateSelector
@@ -370,7 +371,7 @@
             <Grid x:Name="ContentGrid" Grid.Row="1">
 
                 <Grid.ColumnDefinitions>
-                    <ColumnDefinition Width="3*" />
+                    <ColumnDefinition Width="{x:Bind ViewModel.Details.Size, Mode=OneWay, Converter={StaticResource SizeToWidthConverter}}" />
                     <ColumnDefinition x:Name="DetailsColumn" Width="Auto" />
                 </Grid.ColumnDefinitions>