feat: play sound when people is detected & stop it on conditions

[mxmaxime]

When a motion is detected, the system has to ring the alarm, basically "play a sound" for now.

When a motion is detected, we publish a message via mqtt, and the web app receives it.
This app have to publish another mqtt message to ring the alarm.

We should send this message via the web app because, in the future, we might add features like (when a people is here, just notify the resident, so don't ring the alarm, feature #38).

Then, when no motion is detected we publish a new message to stop the sound. It's not the same message as we might add some extra logic to stop the sound as:

• wait a little bit to stop the sound.
• give to the resident the possibility to stop the sound...

⚠️ It's a sensitive feature!

• The sound has to stop when the alarm is switching to off. Don't even search if it's ringing, just publish to stop.
• The sound has to stop after X seconds when a people was detected and then he's gone.