Support for references to color values in Dart

[Lootwig]

Variables that reference a Color are included in highlighting, independent of their name

Motivation and Context

I need to see the colors where I use them, with current version they only show at the declaration, which is in a central theme definition

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-Functional Change (non-user facing changes)

Checklist:

• My code follows the code style of this project (./gradlew check passes clean).
  • Tons of warnings from code I didn't touch
• I updated the version.
• [ x I updated the changelog with the new functionality.

[Lootwig]

@mallowigi while this isn't merged yet (need something from me?), I wanted to add another edge case I discovered - however, I think I'm wasting quite a bit of time on this because I haven't figured out how to run the tests/debug without firing up that heavy test IDE each time - any hints on this?

[mallowigi]

I wanted to release a new version but I got sidelined a bit. I'll see if I can find the time to check the state.

And yes, this needs to run a sandbox version of the IDE. There's a way to run it headless but tbh I didn't really invest times into the tests.