Write (functional) tests for the module

It seems like Gitlab CI can't load the "gutenberg_ai_tools" module because it's in alpha stage:

I added a basic test, for now I suggest you to run the gutenberg tests for now, at least until this module has a tagged release and covered by the security advisory, for now, the Gitlab CI pipeline configuration thinks my module is just garbage.

I'll move it to "Fixed" and I'll create another issue when this module has a stable release.

Automatically closed - issue fixed for 2 weeks with no activity.