Adds a device picker to the MIDI backend config: choose an external synth
(Moog Sub 37, Hydrasynth, etc.), see its parameters grouped and BY NAME with
their CC numbers, tick which ones to control, and Apply — fills the per-output
CC table (CC#/channel/name) and sets the CC count from the template. Clamps to
the engine output count. Self-contained (local state + setParam/setMidiCcCount);
the result lives in the shared params store, so the existing named-preset bar
saves/restores it. Sourced from manifold/src/midi-devices (codegen).
b3c0e71bb7