suggesting_archives: Add GitHub releases search heuristic

The tool already has a GitHub search heuristic for suggesting git repos based on the local archive.

However, this heuristic is not used for suggesting source archives (tarballs). GitHub has a repo-specific API to list all releases: https://docs.github.com/en/rest/releases/releases?apiVersion=2022-11-28#list-releases. In the returned JSON, we can search for the `tag_name` (comparing with the version extracted from the local archive) and then in this tagged release search for `browser_download_url` asset that corresponds to the basename of the local archive.

This will require extracting suggesting-archives-local source code into some shared file, so a small refactoring is a prerequisite.

Start by reading the existing GitHub search heuristic for suggesting git repositories and the suggesting-archives-local source code. Review GitHub's list-releases API response, then trace how the local archive version and basename are extracted. Done means the shared code supports release searches and finds a tagged release asset matching the local source archive.

Written by the indexing model from the issue text.