CmdPal: Handle an empty icon in dock items (#45968)

## Summary of the Pull Request

This PR allows dock to handle items without an icon better:

- Hides the icon element when a dock item is not visible and center text
labels in vertical dock modes.
- Adds an icon to clock dock wrapper, so it appears in settings.
- Stretches buttons with icon and labels in the vertical docks to the
full width.
- Fixes `IconInfoViewModel.IconForTheme` method implementation.

## Pictures? Pictures!

Horizontal Dock:

<img width="393" height="84" alt="image"
src="https://github.com/user-attachments/assets/d12aa406-da9d-4bd2-b464-595deab41d2e"
/>

<img width="390" height="105" alt="image"
src="https://github.com/user-attachments/assets/c28d65c0-1023-47d0-9ff5-85c74a18c342"
/>


Vertical Dock:

<img width="153" height="258" alt="image"
src="https://github.com/user-attachments/assets/e1be59d9-fa1f-4a24-b0c1-e8cff4211906"
/>

Settings:

<img width="1266" height="713" alt="image"
src="https://github.com/user-attachments/assets/722d47da-c668-4df2-9f1d-bf7808333be4"
/>



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

- [x] Closes: #45955

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.TimeDate/TimeDateCommandsProvider.cs

@@ -57,7 +57,10 @@ public sealed partial class TimeDateCommandsProvider : CommandProvider
         var wrappedBand = new WrappedDockItem(
             [_bandItem],
             "com.microsoft.cmdpal.timedate.dockBand",
-            Resources.Microsoft_plugin_timedate_dock_band_title);
+            Resources.Microsoft_plugin_timedate_dock_band_title)
+        {
+            Icon = Icons.TimeDateExtIcon,
+        };
 
         return new ICommandItem[] { wrappedBand };
     }