Split Cropper.js from the main JavaScript manifest.
## What does this MR do?
Splits Cropper.js from the main JavaScript file.
## Are there points in the code the reviewer needs to double check?
That the avatar uploader works. (It did in my testing)
## Why was this MR needed?
Smaller JS payload.
## What are the relevant issue numbers?
#14372
## Does this MR meet the acceptance criteria?
- Tests
- [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 !4978
Fatih Acet
Phil Hughes
Connor Shea