Improved Silent Microphone Detection & Configurable RMS Threshold

We simplified the detection logic for silent microphones. The silence evaluation now runs repeatedly every 5 seconds (instead of just once, after 15 seconds), and evaluates the last 5 seconds. If the value is below the threshold, the warning message is shown to the user. As soon as the instant RMS value exceeds the threshold, the message is removed.

In our tests, the mechanism works better under heavy stress (CPU Burn Loop & DOM Thrash).

The RMS threshold is now configurable through the new pipe-rmsthreshold embed code option.

Build slug: 1c8374a84