Enable LSP in devcontainer and apply rubocop by default

.devcontainer/devcontainer.json

@@ -12,8 +12,16 @@
 
 	// Features to add to the dev container. More info: https://containers.dev/features.
 	"features": {
-    	"ghcr.io/rails/devcontainer/features/activestorage": {}
-  	}
+		"ghcr.io/rails/devcontainer/features/activestorage": {}
+	},
+
+	"customizations": {
+		"vscode": {
+			"extensions": [
+				"Shopify.ruby-lsp"
+			]
+		}
+	}
 
 	// Use 'forwardPorts' to make a list of ports inside the container available locally.
 	// "forwardPorts": [],

.vscode/settings.json

+{
+    "rubyLsp.formatter": "rubocop",
+    "[ruby]": {
+        "editor.defaultFormatter": "Shopify.ruby-lsp",
+        "editor.formatOnSave": true,
+      },
+}