Add support for group-writable roots to managed directories

[xylar]

This is needed for directory used by NCO to point to the latest E3SM-Unified pixi environment.

Checklist

• User's Guide has been updated if needed
• Developer's Guide has been updated if needed
• API documentation lists any new or modified class, method, or function
• Documentation builds cleanly and changes look as expected
• Tests pass and new features are covered by tests
• PR description includes a summary and any relevant issue references
• Testing comment, if appropriate, in the PR documents testing used to verify the changes