Add color prop for checkbox icon

[cnkeats]

fixes #372

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 6106e34:

Sandbox	Source
React	Configuration

[aVileBroker]

So, I know the AC in the ticket said "regardless of the variant and checkbox color" but I don't think that makes sense when actually trying it (see screenshot from codesandbox)

I would think the color prop would just change the general color of the checkbox (in this case where the green is), and we should be able to override the icon color separately

[aVileBroker]

Being able to control both would give us ultimate control

giphy.mp4