API projects/{id}/repository/branches should return a branch creation date as well.
### Description
Whenever I loop through the branches I'd like to know when was the branch created.
### Proposal
Please extend the branches API result to contain this information.
Git wise this information could be extracted like
`git reflog show <branch_name> --date=local`
### Links / references
### Documentation blurb
#### Overview
Add branch create date to the appropriate API resource.
#### Use cases
Whenever you write a script purging old branches it's useful.
### Feature checklist
Make sure these are completed before closing the issue,
with a link to the relevant commit.
- [ ] [Feature assurance](https://about.gitlab.com/handbook/product/#feature-assurance)
- [ ] Documentation
- [ ] Added to [features.yml](https://gitlab.com/gitlab-com/www-gitlab-com/blob/master/data/features.yml)
issue