Metadata: Ignore Exif IFD1 tags with existing IFD0 values to improve standard compliance

[lastzero]

Overwriting IFD0 tag values with values from the same tag in IFD1 is not correct.

See dsoprea/go-exif#40 (comment):

Attribute information is stored in TIFF structure including a File Header, with a maximum of two IFD (0th IFD, 1st IFD). The 0th IFD records attribute information concerning the compressed image (primary image). The 1st IFD may be used to record a thumbnail image.

Thanks to mbethke for figuring this out!

[lastzero]

Changes can be tested in our latest preview build:

https://docs.photoprism.app/release-notes/#development-preview