Originals-to-assets: Option to sort assets into library folders for each library

[Azurae1]

Currently the script sorts posters like this (assuming USE_ASSET_FOLDERS=1)

/ASSET_DIR/Movie1/poster.jpg
/ASSET_DIR/Movie2/poster.jpg
/ASSET_DIR/Show1/poster.jpg
/ASSET_DIR/Show2/poster.jpg

With multiple libraries (for example: Shows, Movies) this results in show and movie folders being in the same directory.

Add a new feature/option to sort them by their library name (according to plex name):
/ASSET_DIR/Movies/Movie1/poster.jpg
/ASSET_DIR/Movies/Movie2/poster.jpg
/ASSET_DIR/Shows/Show1/poster.jpg
/ASSET_DIR/Shows/Show2/poster.jpg