Feature: quantized pitch control voltage input

[theacodes]

This feature would allow configuring either (or both) pitch CV inputs to quantize to the nearest semitone.

Implementation checklist

• [ ] Basic feature implementation, mostly already done in https://github.com/aquaticsarah/Castor_and_Pollux/commit/9e2452c67c6bfa1d0f7cf3d40c0199462d143fb3
• [ ] New settings fields to enable quantization for each oscillator. This requires a couple of changes in a few files- this commit shows what's involved.
• [ ] Update the settings editor to have the fields. This isn't too bad, this commit shows how it was done for the LFO feature, which was a lot more involved than this one.

Possible follow-up features

These are nice to have, but not required to get this feature deployed. They can be added on later.

• Ability to specify a scale other than the chromatic scale.

/cc @aquaticsarah