Reimplementation of the CLI with `typer`

Rationale

The agparse-based CLI became quite large and unreadable.
typer offers automatic documentation, see docs.md
typer offers autocompletion which is faster (based on my very subjective feeling)
- In my experience, the autocompletion Is now reasonably usable without to long wait times
typer offers a better formatted CLI experience

Prompts are now handled via typer.promp, i.e., reprompted if the answer is unclear
If rich is installed, printing is visually more pleasing, e.g.,
- seml --help: without rich
- seml collection status without rich
Since not everyone might like the new printing style, it is optional and printing defaults to the old printing if rich is not installed. To install rich with seml: pip install seml[pretty].

The CLI changed slightly, for instance seml collection delete -s pending staged is now seml collection delete -s "pending staged" or seml collection delete -s pending -s staged.
We now have more code since I explicitly wrapped each function, alternatively we could also adapt a short hand notation as before we directly pass all locals().
Having two different visuals for printing could be confusing?
Are we sure that all parameters are translated correctly?
rich slows down the initial start time by ~200ms, without rich the CLI completion performs better (maybe avoid importing rich if we simply autocomplete?) This is now implemented