Add a progress-bar to milestone pages

Issue #5557 duplicate
Lukas Knuth
created an issue

In the issue-tracker, when opening a mile-stone, it would be nice to have a progress-bar, showing how close to completion that milestone is.

Every issue assigned to a milestone is a "point" on the progress-bar, giving it it's total length (so 10 issues for a milestone would be a progress-bar length of 10) and every issue that is marked as "solved" is a point for the progress.

Example (12 issues, 4 solved):