Fix Mute State during start-up on the boxes

[jlpouffier]

The micro_wake_word.start that was under on_value of the select wake_word_engine_location was triggered during start-up even if the box was supposed to be muted.

This led to a box in a weird state:

• Back screen as if it was muted
• Still able to wake it up

I made that on_value more robust. I added a condition on init_in_progress (because nothing should happen in that stage anyway) More importantly, I added a mute condition when the value changed to On Device to avoid starting micro_wake_word when the device is muted.