project settings: move schema composition settings to own tab

[n1ru4l]

Move the schema position to its own section in the settings instead of having it under general.

from @jdolle #7107 (review)

I like the change to standardize the way we display settings although I'm not entirely sure about the criteria for moving into settings vs keeping as a standalone tab. E.g. we still have an "Alerts" tab for projects that seems suspiciously like a setting to me.

And should Schema Composition and Delete Project be moved to their own sidebar sections now?