Add PowerShell extension (#731)

* Add PowerShell extension

* Bump feature version

src/powershell/devcontainer-feature.json

 {
     "id": "powershell",
-    "version": "1.1.1",
+    "version": "1.2.0",
     "name": "PowerShell",
     "documentationURL": "https://github.com/devcontainers/features/tree/main/src/powershell",
     "description": "Installs PowerShell along with needed dependencies. Useful for base Dockerfiles that often are missing required install dependencies like gpg.",
@@ -21,6 +21,13 @@
             "description": "Optional comma separated list of PowerShell modules to install."
         }
     },
+    "customizations": {
+        "vscode": {
+            "extensions": [
+                "ms-vscode.powershell"
+            ]
+        }
+    },
     "installsAfter": [
         "ghcr.io/devcontainers/features/common-utils"
     ]