Add utility/lock_unlock_poster_art.py

[JonnyWong16]

Add script to automatically lock/unlock posters and artwork in a Plex.

Examples:

• Lock poster for a specific rating key:

  python lock_unlock_poster_art.py --rating_key 12345 --lock poster

• Unlock artwork for a specific rating key:

  python lock_unlock_poster_art.py --rating_key 12345 --unlock art

• Lock all posters in "Movies" and "TV Shows" (Note: TV show libraries include season posters/artwork):

  python lock_unlock_poster_art.py --libraries "Movies" "TV Shows" --lock poster

• Lock all artwork in "Anime":

  python lock_unlock_poster_art.py --libraries "Anime" --lock art

• Lock all posters and artwork in "Movies" and "TV Shows":

  python lock_unlock_poster_art.py --libraries "Movies" "TV Shows" --lock poster --lock art

• Unlock all posters and artwork in "Music" (Note: Music libraries include album covers/artwork):

  python lock_unlock_poster_art.py --libraries "Music" --unlock poster --unlock art