[AC-6510] iOS: Recording AMR Audio

Tested using Titanium SDK 9.0.0.GA What is a valid configuration to record audio in the AMR format. Setting only file format to AUDIO_FILEFORMAT_AMR:

    audioRecorder = Ti.Media.createAudioRecorder({
      format: Titanium.Media.AUDIO_FILEFORMAT_AMR
    });

or with any other compression seems to throw an error:

[ERROR] :  initializing Recorder. Error Error Domain=NSOSStatusErrorDomain Code=1718449215 "(null)"

Shouldn't AMR be declared as a compression instead of fileformat??