fix(files): update loading behavior when changing location

[luka-nextcloud]

• Fix: UX Improvement: Files app: The files grid should be blur or disabled when navigating #63102

Summary

Improves the loading state handling and user experience when navigating in the files list. Ensure that loading indicators are displayed appropriately and that the UI does not show stale or confusing content during transitions.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

[susnux]

This is a sensible area of changes, please add proper tests for the changes behavior (playwright). Moreover this was designed behavior back then to not block users from usage during long running loading. For example the search view should not blank just because the search is in progress.

So besides that point this must get UX approval from designers, because IMHO this is now worse UX than the behavior it tries to fix.

Currently:

• Folder contents A
• navigate
• Folder contents A + loading indicator
• Folder contents B

With this changes:

• Folder contents A
• navigate
• Blank view + loading indicator
• Folder contents B

[susnux]

But this still blanks the table content and shows the loading spinner within the table.
This is not what was said on the issue, the loading spinner within the table is only for new views or initial load.
But when changing folders the top bar loading spinner should be used to be still able to cancel the loading by interacting with the list:

Ideally with the "de-saturation" of the table content as shown in the mockup by @kra-mo