Automate adding binaries to solc-bin during the release

[cameel]

Before we have CI fully handle solc-bin binaries, as described in #13610, we could do a simpler intermediate step towards it that would already make the releases simpler. The idea would be to create a script that downloads the binaries from CI, adds them to a local checkout of solc-bin, runs the update script and posts a PR to github. The script could also upload the binaries to github release page.

We would later use that script in CI as a part of #13610.

[nikola-matic]

Another thing to watch out for - the step should probably use node@16, since I had issues with 18.