Summary:
Component is implemented as a grainjs ui component and can be tested using `yarn serve-projects`.
This diff does not bring color select to Grist just yet.
Follow up:
- Make it possible to set a custom color by typing hex value directly in.
- Disable the button while save call is pending.
Test Plan:
- Adds a project test
Reviewers: paulfitz
Reviewed By: paulfitz
Subscribers: dsagal
Differential Revision: https://phab.getgrist.com/D2733
