Add deduplication

[askiiart]

Describe the enhancement you'd like A menu to remove duplicate photos, possibly with a similar interface to the faces menu.

Describe why this will benefit the LibrePhotos This will allow users to remove duplicate photos from their library.

Additional context None needed.

[zoltarTheGreat]

An alternative is using https://github.com/qarmin/czkawka Maybe just integrating this could help. Havent tried it yet