Add `PlayedUnplayedMixin`

[JonnyWong16]

Description

• Adds PlayedUnplayedMixin for Plex objects which can be marked as played / unplayed which include Audio and Video. Previously, Audio could not be marked as played / unplayed.

  • New property isPlayed.
  • New method markPlayed().
  • New method markUnplayed().

• Deprecated the previous "watched" keywords in favour of uniformed "played" keywords for all media types which also matches Plex Web.

  • Deprecated property Video.isWatched.
  • Deprecated method Video.markWatched().
  • Deprecated method Video.markUnwatched().

Type of change

Please delete options that are not relevant.

• [x] New feature (non-breaking change which adds functionality)
• [x] This change requires a documentation update

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have added or updated the docstring for new or existing methods
• [x] I have added tests when applicable