More platforms/frameworks to support

[atsushieno]

This is a meta/general issue to add platforms and frameworks where new IMidiAccess implementation is desired.

• [ ] wasm : once mono comes up with a usable wasm SDK. It should be possible to bind Web MIDI API objects.
• [ ] Unity : it is actually a framework with multiple platforms:
  • [ ] desktop - it should be (relatively) easily doable by reusing Commons.Music.Midi.DesktopShared implementation classes.
  • [ ] iOS - we can probably reuse own XamMac CoreMIDI implementation (it needs to be built as static)
  • [ ] Android - we need a completely new bindings to Android Java API at Unity level.