[Enhancement] Abilty to change amount of emulated chips for ADL/OPNMIDI via GUI

[freq-mod]

Currently it's only possible via raw MIDI arguments only, but that way there is no way to pass custom bank path. Default value for OPNMIDI seems to be too low and it causes problem with choppy sound on some songs.

[Wohlstand]

That's quick to make, thanks for a remind, will do! 🦊

[Wohlstand]

On a quick hand, I have made few changes to the backend that adds API calls for the ability to change chips count, and I have added an ability to load custom banks by raw MIDI arguments (using x=/path/to/certain/bank.wopn;) 🦊
The GUI of PGE MusPlay I'll update a bit later...