Include rm -rf to dist folder

[ayuhito]

The dist folder end up becoming very polluted at times, especially when you delete a source file which still leaves its bundled-up counterpart in the dist folder. Either cleaning up the dist folder by default or including a --clean flag would be a nice QOL addition.

(Btw, I am happy to make some PRs in the near future for some of these issues I'm making - imo this bundler is the most ideal one out of others I've seen and I'm working on integrating it into the Fontsource project).

[privatenumber]

--clean-dist flag sounds good to me!

[ayuhito]

I was working on this but privatenumber/lintroll#33 is a blocker. Will wait till that's resolved!

[privatenumber]

Feel free to commit with linting violations via --no-verify.