Add milestones to release blocks
What does this MR do?
Adds milestones to release blocks as described in #29020 (closed):
In addition, this MR converts the release_block_spec.js
test from Karma to Jest.
UX specs
With multiple milestones associated:
Note: the footer ("View Issues of Merge Requests in this release") is not implemented by this merge request.
Screenshots
Edited by Nathan Friend