Add a Node script to lint and fix changes

[timothycpoon]

Currently, we have the scripts lint-css-changes, lint-css-fix, lint-js-changes, lint-js-fix. However, if someone wants lint to fix only the changes they introduced, they would need to manually add flags, which can be confusing. The ask would be to add scripts, perhaps named lint-css-changes-fix and lint-js-changes-fix or something similar, which combines the 2 types.

[mizlan]

I like the names lint-css-fix-changes and lint-js-fix-changes (verb-object sorta deal); this is a pretty small PR so if anyone wants to do this, feel free to self-assign