Implement `e` shortcut for editing issues/merge requests

It would be really handy to just press e to trigger edit for issues or merge requests.

cc/ @jschatz1

@JobV Opinion on this?

@jschatz1 I'm a huge fan of shortcuts. No need to ask. Thanks @dblessing.

@alfredo1 this might be a nice small one to get started for you. @jschatz1 can advise if necessary, he did another shortcut before.

Milestone changed to 8.6

Added ~131895 label

Added feature proposal label

Added ~123454 label

Reassigned to @alfredo1

mentioned in merge request !2945 (merged)

I think I should update this, is there any original file for this image somewhere? http://doc.gitlab.com/ce/workflow/shortcuts.html

Nevermind. I figured out, this is the window displayed after pressing "?". I'll add the new shortcut and update the image.

Status changed to closed by commit 52ac5242

mentioned in commit 52ac5242