Speed up shell and CLI invocation with Nucleus installed

[gatli]

Managing imports to late import stuff that is not necessary for most users.

• np, sklearn and shapely on the metrics side (which nobody but our internal services use)
• tqdm notebook is now only loaded in notebooks.
• Shell completion script is now generated once and sourced -> this speeds up shell init considerably and autocompletion

Timing:

pipx install tuna
poetry run python -X importtime cli/nu.py 2>tuna.log
tuna tuna.log

Before

After

[jean-lucas]

nice improvements 😎

[gatli]

nice improvements 😎

❤️