Bias towards local directories for bare editable requirements (#3995)
## Summary
Given `install -e dagster`, we need to assume that the user meant
`install -e ./dagster`, even though `install dagster` should _not_ be
treated as `install ./dagster`. I suspect pip will change this in the
future (since `pip install dagster` does _not_ meant `pip install
./dagster`) but for now it's what users expect.
Closes https://github.com/astral-sh/uv/issues/3994.