Filter diff by filetype

I would like the ability to filter a diff by filetype.

We do code reviews in merge requests, and when a merge request has lots of new images, fonts, and other assets they really clutter up the merge request diff and make code reviews difficult.

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Proposal

Added the filetype dropdown in the "Change between lastest version and master" row.

Filtering the filetype in this merge quest through the dropdown. If the file types are included in the diff, they will also show in the dropdown list. Otherwise, you will not see them in the dropdown list.

Selected one of the type files in the dropdown list. There only show .scss diffs.