Type color hex strings

[sparr]

Brief Description

This PR restricts color strings (color, fill. stroke, etc) to starting with "#". Unfortunately there's no performant way to narrow it down to just hex characters (requires a monstrous union type) or the correct length (requires recursive types or other tricks).

Added one new test line with a bad color.

Checklists

• Test passed
• Coding style (indentation, etc)
• Edits have been made to src/ files not index.d.ts
• Run npm run compile to update index.d.ts

[RiftLurker]

Color strings allow for a lot more options than just RGB strings prefixed with a #.

[sparr]

I see from the official docs that the game drawing functions accept "any web format" for fill/stroke/etc colors. Thanks for pointing me in that direction; I had no idea.