Print associated merge request URL when trying to push an up-to-date branch

Description

Currently, when someone pushes commits to a branch, they are responded with a link to the MR associated with that MR. We should expand this feature to the scenario when someone tries to push to an already up-to-date branch. So, instead of getting Everything up-to-date message, they also get the MR link.

/cc @DylanGriffith