Move file and space actions to files app

[JammingBen]

The file and spaces actions are currently located in web-pkg, where they technically not belong. This has historic reasons, but they should be placed inside the files app and registered/retrieved via the extension system. This would a) create a better separation of concerns and b) reduce web-pkg's total size, which should result in better chunk sizing.

Note that this will be a breaking change, meaning we should first think about when we want to have the next major release.

[JammingBen]

Follow-ups after first iteration via #2456:

• Remove "Create Space from selection" should not appear in batch actions. The extension point for batch actions should not be reflected in the context menu, but in the top bar only. The actions control whether they are applicable for one or many resources in the context menu via isVisible. fixed via fix: context actions is using wrong extension point #2463
• The "Details" action should be present the context menu when selecting multiple resources. fixed via fix: context actions is using wrong extension point #2463
• Actions without category should default to the tertiary category in the context menu. Currently, they are missing completely. fixed via fix: spaces view doesn't have a dedicated multipe select context menu #2464
• Add a dedicated extension point for sidebar actions. fixed via refactor!: add extension point for right sidebar actions, move enable and disable sync actions to web-app-files #2466
• Write deprecation notice for upcoming v7.0.0 (including how to retrieve the moved actions in a third party app)
• Add new extension points to documentation
• Move remaining actions from web-pkg to files app.
• The space actions for setting/editing/deleting the space image should be located in the sub-menu like on the spaces list page. This sub-menu is currently missing on other pages like the search result page.