WIP: fix(encryption): store key by fileId for CollectiveMountPoint

[mejo-]

Summary

In Collectives, we can have different paths to a file by user (when a user changes their user_folder user setting). This leads to inaccessible files with server-side encryption as the encryption keys are stored by file path. In order to fix this, we should switch to fileId based key storage instead of file path based key storage.

TODO

• Decide whether we want to always store encryption keys by fileId, or just for ISystemMountPoint or just for CollectiveMountPoint
• Decide whether we change all the interfaces and functions to pass $fileId through encryption storage wrapper or whether it's acceptable to use $this->rootView->getFileInfo() in Util.php.
• [ ]

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)

AI (if applicable)

• The content of this PR was partly or fully generated using AI