Refresh lockfile when `--refresh` is provided (#15991) (#15994)
## Summary
If you provide `--refresh` to `uv lock`, we'll now always resolve (even
though it might return the same result). This is also robust to
`--locked` such that `--refresh --locked` will only fail if the lockfile
changes.
Closes https://github.com/astral-sh/uv/issues/15997.
