Yarn plugin diffing improvements

[mtlewis]

Summary

The yarn plugin is bundled and minified, and as such diffs when it is updated are not human-readable. It's relevant when the plugin changes though, and adopters might wish to see that it's changed, and in particular verify the checksum of the yarn plugin.

With this in mind, I'm proposing we:

1. Sort .yarnrc.yml and any files in the .yarn directory to the bottom of the list
2. Hide the diff for the yarn plugin by default, with a button allowing interested users to reveal it (similar to how large diffs are handled in GitHub diffs).

Test Plan

What are the steps to reproduce?

Checklist

• I tested this thoroughly
• I added the documentation in README.md (if needed)

[vinzscam]

🙏