Build: add --reset-compare and --clear-compare options to build command

[timmywil]

Summary

This adds 2 options to the build command.

My compare-size cache was getting a little big with all my branches. Rather than manually editing or deleting the file, I would prefer a command that kept the main branch and last run in there (npm run build -- --reset-compare).

I also added --clear-compare in case there's ever a need for starting over completely. It just deletes the cache file.

Checklist

• [x] New tests have been added to show the fix or feature works
• [x] If needed, a docs issue/PR was created at https://github.com/jquery/api.jquery.com

[timmywil]

Sure, that can be configured

[timmywil]

Looking at this again, I think I'll just write to the cache in prettier JSON. Then we can easily edit the cache manually if it gets out of hand.