We lose the more normal looking export in favor of the `return` statement already traditional to this action, and thus can handle await statements without an ESM conversion.
This is a separate commit from the former because I think the next major version of this action should switch to ESM, revert this commit, and use the more standard export notation in all supported languages.
Both of the .cts and .mts flavors. Because this action is written in CommonJS both have to compile to CommonJS in order to execute.
As it is TypeScript there's already an expectation of some slowness, so I went with the approach of running the script via the node VM module. While a cleaner approach, it has the caveat that root level await in the script doesn't work. That should become available if https://github.com/actions/github-script/issues/457 is completed.
`fn.name` was introduced in Node 0.10.0, so this improves test suite maintainability without changing the minimum node version.
Also added a test that for certain proves that Promises can be awaited.
