MR Widget Refactor Part 5
Part 5 of the MR widget refactor work.
Previous MRs, all merged into mr-widget-redesign-review
This MR's target branch is also mr-widget-redesign-review. We are doing this because of incremental reviews. This can be merged into review branch whenever reviewer thinks it's OK. I stop pipelines intentionally, no need to run them since they are all WIP MRs for review only.
Related with #25424 (closed)