Ability to create and export metronome tracks as audio files

Once I create a metronome with a bpm and set amount of bars, I'd like to be able to export it as an audio file

Merged "Export as MP3" #1149

Create a feature that can export the click track, with a specific time and duration, as an MP3 so it can be used for production in a DAW. This makes it easier to go from composition to production and maintain a familiar metronome.