Recommend Azure DevOps extension inside VS-Code for better YAML editing. (#8403)

This enhances the editing experience for YAML inside VS-Code (syntax highlighting and autocompletion).
For more details, see https://marketplace.visualstudio.com/items?itemName=ms-azure-devops.azure-pipelines

.vscode/extensions.json

@@ -2,6 +2,7 @@
   // See https://go.microsoft.com/fwlink/?LinkId=827846
   // for the documentation about the extensions.json format
   "recommendations": [
+    "ms-azure-devops.azure-pipelines",
     "ms-vscode.cpptools",
     "ms-vscode.csharp",
     "ms-vscode.PowerShell",

.vscode/settings.json

@@ -33,5 +33,8 @@
   "powershell.codeFormatting.whitespaceAroundOperator": true,
   
   // Adds a space after a separator (',' and ';').
-  "powershell.codeFormatting.whitespaceAfterSeparator": true
+  "powershell.codeFormatting.whitespaceAfterSeparator": true,
+  "files.associations": {
+    "*.yml": "azure-pipelines"
+  }
 }