Work item color component with edit button

What does this MR do and why?

This MR is part of FE: Work Items - visualize records using colors (#394864 - closed) and delivers the Edit pattern for work item Epic Color widget.

Note: The new UX for Color widget will be delivered as part of !145306 (closed).

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screen Recording 2024-02-22 at 7.59.26 PM.mov

How to set up and validate locally

Prerequisites:

1. Enable the OKRs feature as mentioned in the OKRs docs (e.g. ::Feature.enabled?(:okrs_mvc, Project.find(<PROJECT_ID>)) and the namespace must have Ultimate plan).
2. Enable Epic work items FF - Feature.enable(:namespace_level_work_items)
3. Enable the FF to view the Edit pattern - Feature.enable(:work_item_mvc_2)

Steps to verify:

1. Login with any user
2. Go to any Group > Epic
3. Change the URL from /epics to /work_items e.g. http://127.0.0.1:3000/groups/gitlab-org/-/epics > http://127.0.0.1:3000/groups/gitlab-org/-/work_items
4. Create an new Epic work item
5. Go to the Epic work item detail page
6. Interact with the Color widget

Related to #394864 (closed)