Rewrite MIDI converter without forked Tonejs MidiConvert

[LenweSaralonde]

The MIDI converter needs to perform some processing to the song prior to importing it into Musician. The time/duration note format returned by Tonejs MidiConvert is not convenient to achieve this and requires more unnecessary processing.

TODO:

• [x] Work directly with the raw MIDI data to process tempo changes, pitch bend and sustain pedal events.
• [x] Remove Tonejs MidiConvert
• [x] Pack MUS file from processed raw MIDI format