Add/edit/delete metadata

[jcm4atx]

I'd like the ability to add/edit/delete metadata. This would include subject tags, geolocation data, and perhaps other metadata others might find useful.

Building on this, the ability to create smart folders based on the metadata (e.g. all photos tagged "dogs").

[vauvenal5]

Some metadata feature will be added for sure in future. Regarding smart folders, when the time comes I will first check what the Nextcloud Photos app offers. Syncing albums is planed once the REST API is documented. See also https://github.com/nextcloud/photos/issues/205