Allow ESPHome clients to disable volume control

[kahrendt]

I have the Voice PE route into a receiver, we don’t want to do software volume, but instead let the amplifier do it’s thing.

We would need to omit volume and mute from supported_commands to let MA know.

Control of those would have to be exposed enough via yaml actions/conditions so that a firmware author could fine tune this behavior/let the users configures themselves with something like a select entity

[balloob]

Line-out level: fixed/variable is what Sonos calls it on the Port

[kahrendt]

If we've previously sent a hello message saying we support volume commands and then we switch to aux out mode, just close the connection and reconnect with the updated supported commands in the hello message.

[kahrendt]

Note: the AIC3204 configuration used on a VPE always enables software volume control (that is the recommended approach by TI). We need to determine the exact volume that applies no software changes and use that. We could maybe expose a feature in the audio_dac platform component in ESPHome for this volume, but it may not be possible/available on all existing DACs, so look into this