Ability to index a DataTree with a PurePosixPath

Is your feature request related to a problem?

When working with DataTrees, that are tree-like structure, it is common to have to build paths to access the data contained inside of it. It is then natural to envision pathlib as an help to build such paths, rather than relying on strings. DataTree already uses its NodePath structure internally, that inherit from PurePosixPath

On can already do this:

path = PurePosixPath("/a/b/c/")
xdt: DataTree
xdt[str(path)]

But having to add this str call adds noise to the code.

Describe the solution you'd like

xdt: DataTree
xdt[PurePosixPath("/a/b") / "c"]

Describe alternatives you've considered

Calling str to an existing PurePosixPath is the most natural way: use pathlib to build a path and downgrade to a string accepter by the DataTree indexing logic

Additional context

No response

The issue names the DataTree indexing entry point but no files or tests. Start by locating the DataTree indexing logic and its NodePath handling, then run the relevant indexing tests. Done means a PurePosixPath can be used directly for the shown lookup without changing existing string-path behavior.