Add bulk update support for merge requests list
What does this MR do?
Adds new feature: ability to update multiple merge requests at once from index page (same like we have for issues already)
Are there points in the code the reviewer needs to double check?
I don't think so
Why was this MR needed?
- consistency with issues
- save user time when you want set same label/milestone to 20 merge requests
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
- CHANGELOG entry added
API support added
- 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 you do - rebase it please)
- Squashed related commits together
What are the relevant issue numbers?
Fixes #20087 (closed)