chore: add .vscode/extensions.json to recommend vscode extensions for this workspace (#245)

# Description

- add `.vscode/extensions.json` file to recommend vscode extensions for
this workspace
- add
[`charliermarsh.ruff`](https://marketplace.visualstudio.com/items?itemName=charliermarsh.ruff)
extension

Author: Paulchen5

.vscode/extensions.json

@@ -0,0 +1,6 @@
+{
+  "recommendations": [
+    "charliermarsh.ruff"
+  ],
+  "unwantedRecommendations": []
+}