Add MediaTrackConstraints options for the audio track

[samhirtarif]

Adds feature requested in Issue#44

• Add prop audioTrackConstraints that can be passed to the AudioRecorder component
• The same constraints can also be passed to the useAudioRecorder hook.

Note: In case you are using a combination of AudioRecorder component and useAudioRecorder hook, the constraints should be passed to the useAudioRecorder hook