feat: whittle command line workflows

[timurcarstensen]

closes #229

Features:

• brings cli interface to:
• pretrain, evaluate, finetune, search, chat, serve, download
• KD
• pruning

TODOs:

• whittle compare workflow to compare pruning/kd/nas
• fixed finetuning workflow (maybe update with what gabi has used the last few days)
• tests (can come after paper submission)
• make mypy happy

Notes:

• there's a bug with python 3.12 and argparse (see this issue). To avoid this we need to install jsonargparse[signatures]>=4.35.0 which conflicts with the current version of litgpt that we use. So for now, the cli interface for 3.12 is broken
• In the most recent release of syne-tune on PyPI we get a lot of the warnings/info messages that some dependencies are not installed, this makes the UX not as nice when using CLI workflows since we get those messages multiple times in one CLI workflow. Hence, I switched to installing from source. I could also fix a commit, wdyt @aaronkl ?