This PR removes enso-pack (ensogl-pack) crate.
It still keeps the `enso-runner` JS package, as it is used for CLI argument parser and logger. The runner should be probably refactored (and possible removed altogether).
# Important Notes
I've temporarily extracted the `enso-runner` to `lib/js` directory, as I wanted to avoid keeping pure JS library under `lib/rust`. Attempts at integrating this with `app/ide-desktop` and family caused too much trouble for this PR. The expectation is that the package will be removed or moved elsewhere soon anyway.
