Gretel-client

Various bugfixes and updates

* 🥳 New classification model type added to the CLI.
* 🎉 Updates to Docker volume management when `--runner=local`.
* 🔧 Updates to internal module plumbing and class layout.
* ⚙️ Other various CLI updates and improvements.

First release candidate for the Gretel Beta2 CLI and python SDK 🥳.

🚨 **Please note:** This current `v0.8` release track contains breaking changes from the previous `v0.7` release.

For more information you can read our [blog post about the upcoming Beta2 release](https://gretel.ai/blog/changelog-beta-2).

🐛 Fixes a markdown rendering bug in our documentation.

Improvements to client samplers and readers.