Automate adding binaries to solc-bin during the release

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.

Read the referenced #13610 and the solc-bin update script first, then inspect how CI binaries and GitHub releases or pull requests are currently handled. Done means the workflow downloads CI binaries, updates a local solc-bin checkout, opens a GitHub PR, and can upload the binaries to the release page.

Written by the indexing model from the issue text.