Add options to ignore shared/managed Plex clients

[jjlawren]

Proposed change

The Plex integration currently adds every visible Plex client as a separate media_player entity. This makes some installations very unwieldy as large number of shared clients are dynamically created.

This PR allows you to choose which Plex users' players will create media_player entities via the integration's config options.

It also adds an option (YAML and config option) which ignores shared & managed users as they're granted access to the Plex server.

All clients will still be counted by the integration's sensor for currently playing sessions.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example entry for configuration.yaml:

# Example configuration.yaml
plex:
   host: 10.0.0.5
   token: <PLEX_TOKEN>
   media_player:
     ignore_new_shared_users: true

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Plex ignore shared users home-assistant.io#12132

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

[balloob]

🎉 🎉 🎉

[jjlawren]

If anyone else is willing to validate these changes before we merge, I'd really appreciate it. I'm not certain that this will work in every Plex installation.

[jjlawren]

Updating this PR to use the new multi-select config option UI when that's available (home-assistant/frontend#4247 / #31798). Still WIP for now.

[Kane610]

Smaller comments from me, looks good!

[MartinHjelmare]

Here we're mocking integration code. It would be more robust to just patch the library server and set up the integration so we don't need to mock our own code.

[jjlawren]

Agree, but there are currently no tests which actually set up the integration. I'd like to do that in the future.