CI (CD?): publish server binary periodically

[samcowger]

Building on #113, once there's a CI setup in place to build the server, it should be extended to support publishing a server binary as a build artifact, so users can download it rather than needing to build it from source. This is related to #60, but its focus on leveraging CI for publishing distinguishes it.

Some considerations:

• What platforms should we build for?
  • I would propose a recent Ubuntu and/or macOS to start.
• What conditions should be met to trigger publishing?
  • I would propose publishing whenever a new server version (major, minor, or patch) is tagged and/or released. This pertains directly to Set up release process for VSCode plugin #60. GitHub's documentation on workflows and releases will be useful.
• Where should the artifact be made available?
  • I would propose using this repo's "Releases" section, which I think would follow naturally from a release-driven build process.

I think a great starting point here is to emulate our very own what4-solvers, which builds SMT solvers on multiple platforms and makes their binaries available via periodic releases.