This adds a file to ignore most formatting commits in `git blame`. These
commits usually are not interesting, and being able to skip them makes
it a little easier to traverse a blame history. This is a feature
natively supported by GitHub automatically to ignore these. When running
locally, you need to first configure git to use it.
I was a little on the fence on which PRs to include here. Many of these
are small and probably not too important. However, instead of trying to
figure out some threshold of "is this large enough", I decided to just
include all of them.
I checked these by visually looking at each commit and briefly checking
that it didn't seem to include any non-formatting changes.
I think it would be nice to try to keep commits a little cleaner in the
future, and avoid merging PRs that have things like this (unless it is
due to a change in rustfmt itself). I admit I don't always enforce it
since it can be a significant drag, though.
