fix: Remove patching of PageContent by djangocms-versioning

[fsbraun]

Description

Patching easily introduces side-effects, especially if patches happen at diverse places in the code base. This PR removes the need for djangocms-versioning to patch the core.

Additional interface through CMSConfig

The toolbar is at the heart of django CMS. This PR allows apps to register a mixin for the cms.toolbar.toolbar.CMSToolbar class. All it has to do is to set

class MyCMSConfig(CMSAppConfig)
    cms_enabled = True
    cms_toolbar_mixin = MyMixinClass

djangocms-versioning (and other apps) can use this config instead of patching CMSToolbar. (Example for other use cases: Change the login process through the toolbar)

Creating Version instances when a versioned model is created

So far, djangocms-versioning puts the burden of creating Version objects for versioned models on the app owning the versioned models. To keep the core agnostic of versioning capabilities. This PR (django-cms/djangocms-versioning#300) lets djangocms-versioning automatically create a draft Version object as soon as a versioned object is created. This is achieved by modifying the versioned model's manager's create method.

This removes the need to patch the creation of PageContent objects.

Patches independent of versioning

Quite a few patches of djangocms-versioning are not connected to the versioning capability. They typically are improvement of the core and have been moved into the core with this PR.

Ability to "see" unpublished PageContent objects

A number of patches by djangocms-versioning enable to core to see unpublished PageContent objects. An example are the Page wizards which need to be able to access newly created PageContent objects. This is done by using the Django manager _base_manager in these selected cases.

Related resources

• fix: Remove patching the django CMS core djangocms-versioning#300
• ci: Introduce patching api to avoid side effects with patching #7439 becomes unnecessary with this patch
• [BUG] CMS V4: Copying and pasting an unpublished page renders the page tree unusable #7400 will be solved.

Checklist

• I have opened this pull request against develop-4
• I have added or modified the tests when changing logic
• I have followed the conventional commits guidelines to add meaningful information into the changelog
• I have read the contribution guidelines and I have joined #workgroup-pr-review on Slack to find a “pr review buddy” who is going to review my pull request.

[Aiky30]

Surprisingly a lot of old references to draft still in places. Well found.

Some comments, 2 of any concern:
Page content creation user
Removal of force language, could be replaced / the original requirement sourced back to the wizard changes.

[Aiky30]

Looks good. Read through it thoroughly once again. Nice to have a proper solution to the patching finally.