report <entrypoint> --version in chalk exec

the idea is that when chalk executes something like:

```
chalk exec -- python ....
```

we can figure out that we are executing a `python` program. we can therefore also attempt to call ` --version` or ` version` to report on the version used.

for example that might help in figuring out how many python 2 applications are still deployed across org/etc

Start at the `chalk exec` entry point and trace how the invoked entrypoint is identified. The issue names no files or tests; done means reporting the version of the executed command when a version command can be called.

Written by the indexing model from the issue text.