Feature: store learns to delete prefixes when overwriting/creating hierarchy nodes

[jhamman]

This PR implements delete_dir teaches the Group and Array classes to use it when overwriting nodes in a hierarchy.

Also included here:

• delete_prefix - not used but perhaps we should just use it instead of delete_dir
• changes list_prefix to return absolute paths instead of stripping prefix. Given that list_prefix was unused before, this wasn't very disruptive but calling it out so others can help decide if this is what we want.

Still needs:

• new store tests for delete_dir
• new group tests for edge cases around delete_dir

closes https://github.com/zarr-developers/zarr-python/issues/2191 first steps toward https://github.com/zarr-developers/zarr-python/issues/2108 and #2359

TODO:

• [ ] Add unit tests and/or doctests in docstrings
• [ ] Add docstrings and API docs for any new/modified user-facing classes and functions
• [ ] New/modified features documented in docs/tutorial.rst
• [ ] Changes documented in docs/release.rst
• [ ] GitHub Actions have all passed
• [ ] Test coverage is 100% (Codecov passes)