Create check-dist.yml - #604

Forgot, but certain first party actions have pre and post steps so there are 2 index.js files

This will need some tweaks to take into account dist/restore/index.js and dist/save/index.js

The run failed, dist/ has a different format than I expected 😢 https://github.com/actions/cache/tree/main/dist

Just FYI, we already do something like this -

Whoops, sorry @dhadka I didn't see your comment before I merged. I'm adding the same(-ish) workflow for all actions (see https://github.com/github/c2c-actions-service/issues/2382).

I actually think the existing implementation is a bit cleaner -- didn't occur to me that you don't have to mv the file before calling git diff. I think it makes sense as its own workflow, though. I'll make a follow-up PR.