Make automatic create of personal accounts configurable

[molti-tasking]

For my current projects I have to remove the feature to automatically create a "personal" space on user creation.

This merge request contains mainly:

1. an extra boolean field for the global config to disable this feature.
2. Also the tests crash on my end, this is why I added a if not exists check in if create extension if not exists "basejump-supabase_test_helpers" version '0.0.6';
3. I added a new test file to check the new configuration.

Let me know what you think! :-)

[tiniscule]

Thanks for the PR, have been giving it some thought.

In my projects I use the personal account as a way to let the users configure things specific to their profile, not just as a billable account concept - but maybe that's murky and not the best use case.

Going to play around with this and see if I can think of any consequences to it.