Symlinks could be more obvious in the merge request diff

Problem to solve

Git supports symlinks in repositories, which are committed as blobs with the pseudo-mode 120000 or so. The blob content is the symlink destination. However, this is displayed quite naively in the merge request changes pane.

Target audience

Reviewers, developers

Further details

From https://dev.gitlab.org/gitlab/gitaly/merge_requests/11/diffs#note_146290 :

Screenshot_from_2019-01-21_16-00-54

Proposal

Make the addition, change and removal of a symlink much more obvious from the UI. I don't really know how this would look.

What does success look like, and how can we measure that?

When reviewing an MR or viewing a commit, it is immediately obvious when someone is adding, removing, or changing a symlink, vs. committing a regular file

Links / references

cc @jramsay @jkarthik