Add library recently added methods for each libtype

[JonnyWong16]

Description

Adds a recently added method of each libtype in a library section.

• MovieSection.recentlyAddedMovies()
• ShowSection.recentlyAddedShows(), ShowSection.recentlyAddedSeasons(), ShowSection.recentlyAddedEpisodes()
• MusicSection.recentlyAddedArtists(), ShowSection.recentlyAddedAlbums(), ShowSection.recentlyAddedTracks()
• PhotoSection.recentlyAddedAlbums()

Note: This PR depends on a search sorting fix in #750.

Type of change

Please delete options that are not relevant.

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

Checklist:

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

[Hellowlol]

The test failed. Was this fixed in another PR?

[JonnyWong16]

Yes, it depends on #750.