Add support for input boolean to Google Assistant

[balloob]

Description:

Add support for turning on/off Input Boolean via Google Assistant.

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If the code does not interact with devices:

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

[c727]

also update the docs -> AVAILABLE DOMAINS

[SamuiSmartHome]

Thank you very much for add input_boolean support to google_assistant component. No error with configuration and on HA side to load. However, I cannot link and unlink google_assistant project if there is input_boolean in google_assistant entity_config. So I use the script then be able to link the google_assitant project again.