plugins: added diff command to all plugins and templates

packages/cli/templates/default-app/plugins/welcome/package.json.hbs

@@ -7,7 +7,9 @@
   "scripts": {
     "build": "backstage-cli plugin:build",
     "lint": "backstage-cli lint",
-    "test": "backstage-cli test"
+    "test": "backstage-cli test",
+    "diff": "backstage-cli plugin:diff",
+    "clean": "backstage-cli clean"
   },
   "dependencies": {
     "@backstage/core": "^{{version}}",

packages/cli/templates/default-plugin/package.json.hbs

@@ -9,6 +9,7 @@
     "build": "backstage-cli plugin:build",
     "lint": "backstage-cli lint",
     "test": "backstage-cli test",
+    "diff": "backstage-cli plugin:diff",
     "clean": "backstage-cli clean"
   },
   "dependencies": {