The Web IDE should provide a button to fetch changes from upstream in a forked project

Problem to solve

Sometimes when working on a project via the Web IDE this is done via a fork. If the project was forked at a previous point at time, it may have become out of date with the upstream project. This would make working in the project harder as changes may not be compatible.

Intended users

Anyone who contributes to other projects via a forking workflow.

Proposal

The Web IDE should provide a button to fetch changes from upstream in a forked project. This would update the existing fork so that the user could continue contributing to the project.

Links / references

https://gitlab.com/gitlab-org/gitlab-ce/issues/64040#note_189430871