Add existing functionality to hidden files

[qaeu]

There's a few existing features that are not available to hidden files but I feel should be:

• Searching. No search bar at all when browsing hidden items currently
• De-duplication, and by extension ignoring duplicate uploads to hidden albums
• Moving unhidden files to specific hidden albums
• Moving hidden files to other albums (on android we seem to be able to move them to other hidden albums)
• Machine Learning / people finding