[Request] Bluetooth: Configure visibility

[duhow]

Having Bluetooth in the apartment makes that anybody can connect and cast music (or scary sounds) out of nothing.

While there are several tasks to improve this security in #218 ,

My request for this is to "keep Bluetooth enabled" but add another boolean / check to set visible , so when other devices try to search it, cannot see it. Paired devices (phones) should continue to work.