Add workspace settings for formatter and recommended extensions (#255)

.vscode/extensions.json

@@ -0,0 +1,3 @@
+{
+    "recommendations": ["esbenp.prettier-vscode", "golang.go", "dbaeumer.vscode-eslint"]
+}

.vscode/settings.json

@@ -0,0 +1,4 @@
+{
+    "editor.formatOnSave": true,
+    "editor.defaultFormatter": "esbenp.prettier-vscode"
+}