Add support for all MIDI channels (omni) input in Pure Data & routing output back to Zynthian MIDI router

[Joe-wachter]

Is your feature request related to a problem? Please describe.
Pure Data can solve a lot of customization issues with MIDI routing, such as translating events, remapping CC values, and rerouting MIDI notes to other chains. Currently, Pure Data can only receive MIDI notes on one channel. For example, I'd like to use Pure Data to receive MIDI notes on channels 1-6 from the Fishman TriplePlay MIDI guitar pickup and send different notes to different chains depending on the channel and note.
Describe the solution you'd like
In MIDI-only chains, there is an option to listen to all channels and then route the output back to the main midi router. I'd like this to be available on Pure Data chains as well.
Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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