Support for native BSD backends

[jcelerier]

Multiple possibilities:

https://hellosystem.github.io/docs/developer/midi.html

https://man.openbsd.org/midi.4

https://sndio.org/

[jcelerier]

@yurivict what makes the most sense?

[yurivict]

@jcelerier

JACK definitely supports MIDI and runs fine on FreeBSD.
I only used virtual MIDI flows - I don't have any hardware MIDI devices.

SNDIO is also available and supports MIDI.

PulseAudio also supports MIDI.

Some other interfaces probably support MIDI as well.

IMO all audio software interfaces capable of supporting MIDI should be either supported by libremidi, or should be listed in the "desired" list.