In PR #3514, we added a `/api` directory for functions and a `/public` directory which was created at build time.
This moves the build script to be `now-build` so we don't don't need to build everything in the repo and also no longer need to special case the git env vars.
This adds initial support for Windows in GitHub Actions CI tests.
There is still work to be done to prevent certain tests from hanging in CI so those are skipped for now.
I was getting errors when running `yarn build` locally because the public directory already exists.
This will make sure the public directory is deleted before generating it again.