WIP: Add a Milestone progress bar on Issue

What does this MR do?

Add a Milestone progress bar on Issue page.

Are there points in the code the reviewer needs to double check?

• In a compact view of the side bar, we may need to fix css more.

Why was this MR needed?

This MR allows users to notify the progress of the milestone for the issue.

Screenshots (if relevant)

See #26862 (moved)

Updated:

Normal view

Compact view

Does this MR meet the acceptance criteria?

• Changelog entry added
• [n/a] Documentation created/updated
• [n/a] API support added
• Tests
  • [n/a] Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #26862 (moved)