Update vscode extension recommendations (#23044)

### Description of Change

We were recommending some now less than useful extensions. This updates
the recommended extensions to be: C# Dev Kit, C# Intellicode, and GitHub
CoPilot Chat, which will pull in their required dependencies as well.

Author: PureWeen

.vscode/extensions.json

@@ -1,7 +1,7 @@
 {
     "recommendations": [
-      "ms-dotnettools.csharp",
-      "ms-vscode.mono-debug",
-      "visualstudioexptteam.vscodeintellicode",
+      "ms-dotnettools.vscodeintellicode-csharp",
+      "ms-dotnettools.dotnet-maui",
+      "github.copilot-chat"
     ]
 }