Remove files from loading in the PR that match excluded files

With the current Exclude File feature in a Pull Request, it excludes the diff from loading but does not exclude the file from being in the PR list.

With the PR file list limits being at 999 files, if we could remove excluded files from loading, we could give capacity for the other non-excluded files to load before hitting the limits.

Suggestion is to : Completely not load the files that match the excluded file feature, so they don't show up as part of the diff as well as the file list.

We could also probably put a banner saying, excluded files aren't displayed in the PR. (This is to avoid confusion of wether the file is part of the merge or not)