Mark a file with a level of importance in a pull request

Pull requests often have files that are more or less important than others. While I can use comments to point out important or insignificant changes I'd like the ability to mark a file as "not worth looking at" which could collapse the contents in the page. I'd also like to be able to mark a file as important where it is highlighted in some way.

Collapsing project files or code files with only formatting changes would help clean up large pull requests and allow reviewers to focus on the important parts of a pull request.