Add support for Mode trait in Google Assistant.

[marchingphoenix]

Description:

Add support for Modes Trait for Google Assistant.
Requires a pre-defined set of definitions for "settings"
https://developers.google.com/actions/reference/smarthome/traits/modes
Code will try to match media_player sources to available settings and present them to Google Assistant.
Modes are currently only supported by media_players but the structure is there to support other device TYPES as needed.

Related issue (if applicable):
Relates to feature request here:
https://community.home-assistant.io/t/control-denon-receivers-via-google-assistant/80126

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#7683

Example entry for configuration.yaml (if applicable):

No changes.

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

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

• Documentation added/updated in home-assistant.io

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

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc
  Not applicable..

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[michaelarnauts]

There are still a few duplicates or comma's.

[balloob]

Nice! 🎉

[hf1985]

Does this mean that Home Assistant will soon support controlling my Bluesound media player with Google Assistant, which does not work right now?

[marchingphoenix]

I never had issues turning on and off my receiver during testing.
Looking at the media_player.bluesound code, that component does not support the on/off feature in HA.

[hf1985]

Looking at the media_player.bluesound code, that component does not support the on/off feature in HA.

That makes sense to me, since you would not want to turn your Bluesound media player on/off, you would want to make it play/pause. Might there be a way to turn the Google Assistant command “turn media player on/off” into the HA service call “media_player.media_play/media_player.media_pause”?

[marchingphoenix]

This is a bit off topic for this pr. Any change would affect all media_players, I'm not sure if that's something we'd want to do. Might be able to reverse engineer what GA does for chromecasts.

[hf1985]

Wouldn't it be both possible and relevant to make the module ask (sorry for my layman language, I have no idea about the technical side of this): "Does this media player support on/off?" "No." "Okay, I'll sent play/pause commands instead"?

[hf1985]

Or would it be possible with the mode trait supported to enable a command like "set media player to play" and "set media player to pause"?

[balloob]

No discussion in merged PRs.