[tests] Add tests for examples (#9403)

These tests will run if one of the conditions is met:

- any change to `./examples`
- any changes to `./packages/frameworks`

The test ensures that examples can build and deploy without errors.

In a future PR, we could improve these tests to make requests to the
test deployment (like we do for probes).

examples/blitzjs/package.json

@@ -8,6 +8,9 @@
     "lint": "eslint --ignore-path .gitignore --ext .js,.ts,.tsx .",
     "test": "echo \"No tests yet\""
   },
+  "engines": {
+    "node": "16.x"
+  },
   "browserslist": [
     "defaults"
   ],