Support bare executables in releases

[filiptibell]

Similar in implementation to #4, we could also support bare executables (not zipped or tarballs) in tool releases. One example and a tool I know of that does this is Sentry: https://github.com/getsentry/sentry-cli/releases/tag/2.31.0

Bare executables are sometimes accompanied by zips and tarballs (as seen in the linked release), and if we support bare executables we should probably still prefer zips/tarballs, since download sizes and network latency are generally the bottlenecks for Rokit.