Allow users to specify URLs in `project.dependencies` and `tool.uv.sources` (#9718)
## Summary
This PR allows users to specify a source both in `project.dependencies`
("production") and `tool.uv.sources` ("development"). It's not intended
as a holistic fix for "production" vs. "development" dependencies, but
in some cases this is good enough with `--no-sources`, and I don't see a
great reason for enforcing it right now.
Closes: https://github.com/astral-sh/uv/issues/9682
Ref: https://github.com/astral-sh/uv/issues/7945 (but I'll leave this
open?)