Implement rye test command built on pytest

[mitsuhiko]

This is an extension to #762 with some differences:

• This runs pytest once for each project in the workspace. This means that per pyproject.toml settings are honored
• It does not automatically add pytest to the pyproject.toml but lets the user do that
• It automatically syncs if enabled to bring pytest into the venv

This still needs tests.

Replaces #762