Implement note color scheme style options

Problem

Currently, the only ways to affect the color of notes are:

• Using the 'Color Notes' plugin, which comes pre-installed with MSS and colors notes specifically for Boomwhacker notation
• Individually selecting notes and changing their color in Properties > Appearance

There's an opportunity to allow users to create custom color schemes for their notation, as well as apply presets for other existing schemes like Figurenotes Stage 3 (the latter of which will also require adding a notehead shape scheme, but this can be built later).

Task

Add a new 'Color' section to the Notes page of the Style dialog.

See the full spec in Figma here: https://www.figma.com/design/TtiqS2aXqfua37BPzj9C1g/Community-projects?node-id=6-35

Once built, we can also remove the 'Color Notes' plugin (or, keep it, and just make it switch the color preset to 'Boomwhackers').