Allow managing face clusters through DAV

[marcelklehr]

URL schema is:

/dav/recognize/<user>/faces/<person-name>/<id>-<filename>

Face clusters can be renamed using MOVE, files can be assigned to a different cluster using MOVE, both can be removed using DELETE.

• Add PROPFIND handler for face position in the picture, maybe?

Based on nextcloud/photos#1146

[icewind1991]

files can be assigned to a different cluster using MOVE

I've been using COPY instead of MOVE for operations like this as it seems more appropriate to me (the resource stays at the old location)

Edit: misunderstood, thought this was about assigning untagged faces to a tag, but this is about moving faces to a different tag.

[icewind1991]

Overall approach looks good

[marcelklehr]

Thank you for reviewing! ♥️

[juliusknorr]

Forgot to send

[juliusknorr]

Small optimisation comment, but otherwise looks good