CmdPal: Arrow keys move logical grid pages (#43870)

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## Summary of the Pull Request

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## PR Checklist

- [X] Closes: #41939
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## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed
Before

![Before](https://github.com/user-attachments/assets/49853e8d-9113-425c-8230-e49fb9b8d640)

After

![After](https://github.com/user-attachments/assets/a4597fe6-6503-4502-99cf-350425f5ef51)

I noticed the double "active" line around the items when the ListPage is
focused. I was unable to find where that is defined. Ideally, the
black-border would go away.

I tested with AOT turned on.

The behavior accounts for suggestions. If the SearchBar is focused and
there is a suggestion, right-arrow will [continue] to complete the
suggestion.

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/SearchBar.xaml.cs

@@ -208,21 +208,32 @@ public sealed partial class SearchBar : UserControl,
 
             e.Handled = true;
         }
+        else if (e.Key == VirtualKey.Left)
+        {
+            // Check if we're in a grid view, and if so, send grid navigation command
+            var isGridView = CurrentPageViewModel is ListViewModel { IsGridView: true };
+
+            // Special handling is required if we're in grid view.
+            if (isGridView)
+            {
+                WeakReferenceMessenger.Default.Send<NavigateLeftCommand>();
+                e.Handled = true;
+            }
+        }
         else if (e.Key == VirtualKey.Right)
         {
             // Check if the "replace search text with suggestion" feature from 0.4-0.5 is enabled.
             // If it isn't, then only use the suggestion when the caret is at the end of the input.
             if (!IsTextToSuggestEnabled)
             {
-                if (_textToSuggest != null &&
+                if (!string.IsNullOrEmpty(_textToSuggest) &&
                     FilterBox.SelectionStart == FilterBox.Text.Length)
                 {
                     FilterBox.Text = _textToSuggest;
                     FilterBox.Select(_textToSuggest.Length, 0);
                     e.Handled = true;
+                    return;
                 }
-
-                return;
             }
 
             // Here, we're using the "replace search text with suggestion" feature.
@@ -232,6 +243,20 @@ public sealed partial class SearchBar : UserControl,
                 _lastText = null;
                 DoFilterBoxUpdate();
             }
+
+            // Wouldn't want to perform text completion *and* move the selected item, so only perform this if text suggestion wasn't performed.
+            if (!e.Handled)
+            {
+                // Check if we're in a grid view, and if so, send grid navigation command
+                var isGridView = CurrentPageViewModel is ListViewModel { IsGridView: true };
+
+                // Special handling is required if we're in grid view.
+                if (isGridView)
+                {
+                    WeakReferenceMessenger.Default.Send<NavigateRightCommand>();
+                    e.Handled = true;
+                }
+            }
         }
         else if (e.Key == VirtualKey.Down)
         {
@@ -274,6 +299,8 @@ public sealed partial class SearchBar : UserControl,
 
                 e.Key == VirtualKey.Up ||
                 e.Key == VirtualKey.Down ||
+                e.Key == VirtualKey.Left ||
+                e.Key == VirtualKey.Right ||
 
                 e.Key == VirtualKey.RightMenu ||
                 e.Key == VirtualKey.LeftMenu ||