Support PEP 794

PEP 794 adds two fields to pyproject.toml: import-names and import-namespaces. These fields are only to support tooling, and don't have any functional impact on distributions.

Hypothesis provides four modules, so we would add:

[project]
import-names = [
    "hypothesis", 
    "_hypothesis_globals ; private", 
    "_hypothesis_ftz_detector ; private", 
    "_hypothesis_pytestplugin ; private",
]

This PEP was just accepted and hasn't yet been implemented in all the relevant tools, so I expect we'll have to wait a bit before implementing this.