Add last commit time to repo view

## What does this MR do?
Adds the last commit time to the repository file view

## Are there points in the code the reviewer needs to double check?
Just need to make sure it works well in responsive (It is working well to my knowledge 😃 )

## Why was this MR needed?
Allow users to see more information related to the last commit

## What are the relevant issue numbers?
Closes #20224 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-07-27_at_1.54.03_PM](/uploads/2b3da5c6b82965fd302abe590d2b0e46/Screen_Shot_2016-07-27_at_1.54.03_PM.png)

After:
![Screen_Shot_2016-07-27_at_1.54.09_PM](/uploads/1f5f5fe1bd6f193090067a41ac4e3c66/Screen_Shot_2016-07-27_at_1.54.09_PM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5530