Subcommand for generating conda environment files.

[analog-cbarber]

Add new subcommand for generating conda environment files from pyproject.toml dependencies.

This should handle environment markers and should provide options to include extra dependencies
using both extra marker and tool specific lists (e.g. poetry).

[analog-cbarber]

Probably just emulate the conda env command, e.g.:

• whl2conda env export - generate environment file
• whl2conda env create - create environment
• whl2conda env update - update environment

[analog-cbarber]

Some references;

• hatch
• poetry
• PDM

[analog-cbarber]

This would depend on #25