midi: don't convert Midi in nodes

Avoid doing conversions in the nodes between Midi formats, just assume
the imput is what we expect and output what we naturally produce.

For ALSA this means we produce and consume Midi1 or Midi2 depending on the
configurtation.

All of the other modules (ffado, RTP, netjack and VBAN) really only
produce and consume MIDI1.

Set the default MIDI format to MIDI1 in ALSA.

Whith this change, almost everything now produces and consumes MIDI1
again (previously the buffer format was forced to MIDI2).

The problem is that MIDI2 to and from MIDI1 conversion has problems in
some cases in PipeWire and ALSA and breaks compatibility with some
hardware.

The idea is to let elements produce their prefered format and that the
control mixer also negotiates and converts to the node prefered format.
There is then a mix of MIDI2 and MIDI1 on ports but with the control
port adapting, this should not be a problem.

There is one remaining problem to make this work, the port format is
taken from the node port and not the mixer port, which would then expose
the prefered format on the port and force negotiation to it with the
peer instead of in the mixer.

See #5183

spa/plugins/alsa/alsa-seq.h

@@ -82,6 +82,8 @@ struct seq_port {
 	struct spa_pod_builder builder;
 	struct spa_pod_frame frame;
 
+	uint32_t control_types;
+
 	struct spa_audio_info current_format;
 	unsigned int have_format:1;
 	unsigned int active:1;