Package from a Wheel

Nobody has claimed this yet.

I have a large number of existing python projects, but I would need to make a significant time investment to get PyOxidizer to work in all the projects. I do however have them all generating wheels as part of my build pipeline.

Would it be possible to add some UX/UI tweaks to make (at least) simple, pure python projects work by just pointing the PyOxidizer to the wheel and telling it which console script to use as the default? Essentially stealing `shiv`'s CLI for simple things.

```bash
# for example, to package project `foo`
pyoxidizer --console-script foo --output-dir ./dist/ /path/to/some/foo-X.Y.Z-py3-none-any.whl
```

I know I can make a venv and then package from there but that always fails. Having a sure fire way that is known to work would be great specially if most python developers could utilize pre-exiting build artifacts.

The issue names no source files or tests. Start by tracing PyOxidizer's CLI entry point and its existing Python environment or package ingestion path, then check how a wheel and its console-script metadata could be handled. Done means a simple pure-Python wheel can be packaged by specifying the wheel and default console script, with coverage for the command-line workflow.

Written by the indexing model from the issue text.