Support for sidecars living in a secondary folder hierarchy

Some applications write metadata sidecars to a wholly different tree from the originals. As an example, for /originals/2023/07/IMG_1234.jpg, they’d write the sidecar to /storage/2023/07/IMG_1234.yml.

This should track adding support for this situation.

(additionally: we should probably ignore the Taken value if TakenSrc is meta)

That would be good. I have one ‘originals’ folder exported from Google Photos and two libraries reading it. Photostructure and Photoprism. Sure I would like having one, but that’s probably won’t happen. Also both scan new photos from one folder and … That won’t end lol. I consider Photostructure being my main library and I like it more, but it is limited and I need other one too (even for maintaining main).

Also I don’t like docker, . appimage is more convenient. I also never tried running Photostructure in docker, but thought if it is better. Idk.