Don't read metadata from stale `.egg-info` files (#9760)
## Summary
We were reading an `.egg-info` file from the root directory that didn't
apply to the root member -- it was for another workspace member. I think
this is driven from some idiosyncracies in the `setuptools` setup for
that workspace member, but it's still wrong to fail.
This PR adds a few measures to fix this:
1. We validate the `egg-info` filename against the package metadata.
2. We skip, rather than fail, if we see incorrect metadata in an
`egg-info` file or similar. This is an optimization anyway; worst case,
we try to build the package, then fail there.
Closes https://github.com/astral-sh/uv/issues/9743.
