No longer save asset catalogs on blendfile save. Instead:
- extend the confirmation prompt for unsaved changes to show unsaved
catalogs.
- In the confirmation prompt, make catalog saving explicit & optional,
just like we do it for external images. {F10881736}
- In the Asset Browser catalog tree, show an operator icon to save the
catalogs to disk. It's grayed out if there are no changes to save, or
if the .blend wasn't saved yet (required to know where to save the
catalog definitions to). {F10881743}
Much of the work was done by @Severin and reviewed by me, then we
swapped roles.
Reviewed By: Severin
Differential Revision: https://developer.blender.org/D12796
Add `blender::bke::AssetLibraryService` class that acts like a
blendfile-scoped singleton. It's allocated upon the first call to
`BKE_asset_library_load` and destroyed in the LOAD-PRE handler.
The `AssetLibraryService` ensures that edits to asset catalogs are not
lost when the asset browser editor closes (or even reloads). Instead,
the `AssetLibrary` pointers it owns are kept around as long as the blend
file is open.
Reviewed By: Severin
Maniphest Tasks: T92151
Differential Revision: https://developer.blender.org/D12885
