Address feedback from internal review

- use the new MongoDB-owned package name (mongodb/laravel-mongodb): OK!
- rename /api/ping/ to /api/test_mongodb/ to be consisten with /test_mysql/

`php artisan migrate:refresh` works, after both databases are accessible

Misc:
init_repo.sh now launched automatically if using devcontainer, since it's defined in devcontainer.json

Author: hubertnguyen

src/composer.json

@@ -8,7 +8,7 @@
         "php": "^8.0",
         "fruitcake/laravel-cors": "^2.0.5",
         "guzzlehttp/guzzle": "^7.2",
-        "jenssegers/mongodb": "^3.9",
+        "mongodb/laravel-mongodb": "^3.9",
         "laravel/framework": "^9.0",
         "laravel/sanctum": "^2.14",
         "laravel/tinker": "^2.7"