resolution & GPS accuracy for pictures & sequences, cleanup proprietary EXIF fields

Depends on !337 (merged) (as it needs sensor_array_dimensions computing)

This PR adds new fields for picture resolution & GPS accuracy (related to #195 (closed)) in DB, computes values for already imported pictures, offer these new fields in API response and vector tiles. And as we're making a whole rewrite of pictures table, I took the opportunity to do some EXIF cleanup (remove all proprietary EXIF fields with hex keys, a part of them being quite long with no added value).

Also, made the choice to offer raw values instead of a pre-computed photoscore, as it may evolve with time, and each re-user may need different values... So anyone can filter like they want. For Panoramax, web-viewer will set-up its own criteria based on ongoing discussions. It will make this more future-proof (to avoid re-read from metacatalog if score computation changes).