Fix: remove views from projects if catalog is changed

[m6121]

Description

As described in #1198, if the project's catalog is changed, views that are no longer available are not remove. This PR implements this.

In addition, it sketches the addition of now available views to the project. However, as the user is not available, this is not yet working. If we find a solution, we might similarly, add this if the view is changed in the management interface which currently also implements the removal only.

As the buildin signal post_save does not contain the request object, we may need to move to a custom signal in order to enable filtering based on groups and availability for the user.

ToBeDone:

• Add tests
• Decide on automatically adding views to projects (maybe also enabled by setting?)
• Change to custom signal/include filtering of views based on user permissions
• Implement adding of views to other signals.

Related issue: #1198

[m6121]

Hi @jochenklar and @MyPyDavid, what do you think about automatically adding views to projects on either user change of the catalog or change of the view <-> catalog relation within the management interface?

[coveralls]

coverage: 90.476% (-0.002%) from 90.478%
when pulling 4c83585 on fix/1198-views-catalogs-change
into 1eadee5 on main.

[MyPyDavid]

we still need to think and discuss about this

• probably with a feature flag for this settings
• or couple the Views with Catalogs strictly?
• I can add this method also for tasks to keep it consistent across the models
• ...

[jochenklar]

I wrote something in #1198. (I needed to look it up, we already have a feature flag, is used in rdmo/projects/apps.py)