[mqtt.homeassistant] Implement JSON schema lights (#13808)

[mqtt.homeassistant] Implement JSON schema lights (#13808)

* [mqtt.homeassistant] implement JSON schema lights
* [mqtt.homeassistant] use enum for current state of color mode
* [mqtt.homeassistant] use implicit lambdas
* [mqtt.homeassistant] remove string constants in favor of an enum
* [mqtt.homeassistant] allow sending ON and brightness commands through bare
* [mqtt.homeassistant] turn down debug logging

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Signed-off-by: Cody Cutrer <cody@cutrer.us>