Add controls to the UI

[djtuBIG-MaliceX]

The UI is literally just the IPlugInstrument example.

Make it useful.

Things to add

• [ ] Channel selection
• [ ] Program change list
• [ ] Basic CC controls (volume, pan, expression etc.)
• [x] Pitch bend range (wire it up to 0-0-2 RPN by default)
• [ ] Coarse Tune
• [ ] Fine Tune
• [x] Elongate keyboard to 61 keys and transpose buttons
• [x] Reverb switches 0/1/2 (currenly hardcoded to 1)

[djtuBIG-MaliceX]

Ensure UI controls can be persisted between launches (eg: state reload)