Merge branch 'temp-review-asset-browser-ui' into asset-browser

Merge branch 'temp-review-asset-filelists' into temp-review-asset-browser-ui

Fix crash when splitting area with invisible file browser data

Merge branch 'temp-review-asset-filelists' into temp-review-asset-browser-ui

Undo unnecessary int type change

Undo unnecessary int type change

Avoid unsafe access to asset browsing through BPY

Python could access asset selection params even though the browser was in file
browsing mode. The value of that data would be undifined then.

Address review comments

Don't run thread-unsafe file-list reading in threads

Fix compile errors after merge

Merge branch 'temp-review-asset-filelists' into temp-review-asset-browser-ui

Refactor how we store ID and asset data references in file lists

* Remove ID-map and ID session-UUID code, we can now reference the ID directly.
* Store imported asset metadata separately.
* Because of that, `FILE_TYPE_ASSET_EXTERNAL` could be removed.
* Get asset metadata of the current files via the ID directly.
* Move local data references into a nested struct, to group them together and
allow a clear comment on how they must be updated.
* Improve comments and note how the local data needs to be updated.

Fix invalid memory use of "Current File" after undo & deleting data-blocks

Implement proper mechanisms to ensure the file list is recreated after undo,
data-blocks are removed, assets created/removed or file loading without UI.
This could be further improved (e.g. don't recreate it if no asset data-block
is affected by undo or deletion).

Addresses T82886 & T83242.

Fix invalid memory use of "Current File" after undo & deleting data-blocks

Implement proper mechanisms to ensure the file list is recreated after undo,
data-blocks are removed, assets created/removed or file loading without UI.
This could be further improved (e.g. don't recreate it if no asset data-block
is affected by undo or deletion).

Addresses T82886 & T83242.

Don't allow selecting single .blend's as Asset Libraries for now

Always select a directory - although this could contain a single .blend file of
course. But this will make it easier to add the index/cache in future because
it could just be placed in this directory.

Finish support for directories as Asset Libraries

I recently found out that the file reading code already supports listing the
data-blocks from all .blends in a directory. All that was left to do was making
sure drag & drop works, which is what this commit fixes.

Addresses T82682.

Merge branch 'temp-review-asset-browser-ui' into asset-browser

Missed another one

Correction to previous commit

Missed something in last commit