Ability to customise default merge request title
#### Description
Ability to customise default merge request title.
>We want to give default name in title box.["branchname:"]
>Please see the screen shot, i want the "branchname:" in title automatically.
#### Proposal
Provide the ability to customise the default merge mequest title. Currently this is the last commit message title, this could be changed to "branch" title for example.
#### Links / references
+ https://gitlab.zendesk.com/agent/tickets/41442
issue