Fix root of `uv tree` when `--package` is used with circular dependencies (#15908)
Closes #15907
Best viewed with
https://github.com/astral-sh/uv/pull/15908/files?diff=unified&w=1
When `--package` is used, just use those as the roots rather than
calculating them. I'm not sure if there will be undesirable
side-effects, but it's the naive solution.