Add helpful info to MR sidebar

Description

Often, I'm reading through the depths of an MR and then decide I want to checkout the branch. To do this, I have to scroll up to the top to get the branch name, which causes me to lose my place in the comments 😞.

Is there a cool place in the sidebar where we could add the branch name (and potentially other helpful info)?

What info could be potentially helpful?

• Source branch (and if on fork, the "Check out branch" button is really helpful)
• Target branch
• Commit ID
• Pipeline status
• Related issue
• Related MR

Why is this helpful?

This information is commonly used for reviewing / understanding a MR. It'd be really nice if they were always visible so that I don't lose track of my position in the body.