add generate_database cli

[leocov-dev]

added cli entrypoint for the generate_database function.

we need to be aware that since this adds an executable script inside .venv/bin (or other install location) there is the potential for name clashes with other libraries. the name generate_database may be too generic so I made it tetra3-gen-db.

after installing the library you may:

# minimum required arguments
tetra3-gen-db --max-fov 30 <path/to/database> <path/to/target.npz>

# read help
tetra3-gen-db -h

Notes:

The deprecated argument simplify_pattern is not included in the cli flags.

I experimented with automatically generating the flags based on the signature but some of the argument types are complex and the effort is not worth it I think.