[Microphone Indicator] Show name of microphone being used

When having multiple microphones (e.g. internal and headset) connected
to a system it can be useful to know which microphone the application
is using, for instance so that you immediately see when your conferencing
solution is set up to use the wrong microphone.

Signed-off-by: Eike Hein <eike.hein@mbition.io>