Show MR link in pipeline list view

Description including problem, use cases, benefits, and/or goals

In the list of pipelines, we show some meta information about the pipeline such as the branch and commit that triggered the pipeline run. Let's add the merge request number and link to MR, if there is one. Also, add a filter for Merge Requests similar to Branches so you can see the last pipeline run for each (open) MR. As a product manager, I'm more concerned about the status of merge requests than individual branches and commits.

Proposal

The title of the Commit column might need to change.

Links / references

/cc @ayufan