Add GitHub Actions workflow to build the offline release

[fenhl]

Automates building the offline releases for https://ootrandomizer.com/downloads so they can hopefully be made available sooner/immediately after future releases.

@TreZc0 @dragonbane0 a couple questions for the website maintainers:

1. Is there any particular reason there are separate macOS downloads for Apple Silicon and Intel right now? If not, I'd propose having GHA build a Universal binary instead.
2. What would be the best way to pass the build artifacts to the website?

Testing

The workflow is temporarily enabled on PRs to Dev as well, so it should run for this PR. Once the PR is done and CI passes, I'll remove that trigger so it only runs for actual releases.