[FR]: js_image_layer support for distroless images

### What is the current behavior?

Right now if you use `js_image_layer`, it creates a [bash launcher](https://github.com/aspect-build/rules_js/blob/main/js/private/js_image_layer.bzl#L201) which typically we use as the entrypoint for running the program built by `js_binary` in a containerized environment.

This works fine, but there is a requirement on using an image with `bash` available in it. For security reasons, it may be desirable to use [distroless images](https://github.com/GoogleContainerTools/distroless) and one of the things they avoid is having the ability to shell into the container/pod.

### Describe the feature

It would be nice for `js_image_layer` to also support a launcher that doesn't rely on bash. One option is to support native launcher (maybe written in go as example or a prebuilt binary) that preserves the behavior of the program (the environment variable and making runfiles available). We wrote a custom rule for this ourselves and packaged it as the entrypoint in rules_js. There's possibly other options too, I'm probably not aware of.

It feels like this could be part of rules_js with `js_image_layer` as this could be a common usecase but I understand if you think owners of apps need to build this tooling themselves (in which case we can close this issue).

Start with js/private/js_image_layer.bzl at the launcher creation referenced in the issue, then trace how js_image_layer invokes js_binary in a container. Compare the existing bash launcher behavior with the stated requirements for environment variables and runfiles, and review the distroless constraint. Done means js_image_layer supports a launcher that works without bash while preserving those behaviors.

Written by the indexing model from the issue text.