Closes pydata#757
Closes pydata#2852

* main: (63 commits)
  Add close() method to DataTree and use it to clean-up open files in tests (pydata#9651)
  Change URL for pydap test (pydata#9655)
  Fix multiple grouping with missing groups (pydata#9650)
  flox: Properly propagate multiindex (pydata#9649)
  Update Datatree html repr to indicate inheritance (pydata#9633)
  Re-implement map_over_datasets using group_subtrees (pydata#9636)
  fix zarr intersphinx (pydata#9652)
  Replace black and blackdoc with ruff-format (pydata#9506)
  Fix error and missing code cell in io.rst (pydata#9641)
  Support alternative names for the root node in DataTree.from_dict (pydata#9638)
  Updates to DataTree.equals and DataTree.identical (pydata#9627)
  DOC: Clarify error message in open_dataarray (pydata#9637)
  Add zip_subtrees for paired iteration over DataTrees (pydata#9623)
  Type check datatree tests (pydata#9632)
  Add missing `memo` argument to DataTree.__deepcopy__ (pydata#9631)
  Bug fixes for DataTree indexing and aggregation (pydata#9626)
  Add inherit=False option to DataTree.copy() (pydata#9628)
  docs(groupby): mention deprecation of `squeeze` kwarg (pydata#9625)
  Migration guide for users of old datatree repo (pydata#9598)
  Reimplement Datatree typed ops (pydata#9619)
  ...

* main:
  Add `DataTree.persist` (pydata#9682)
  Typing annotations for arithmetic overrides (e.g., DataArray + Dataset) (pydata#9688)
  Raise `ValueError` for unmatching chunks length in `DataArray.chunk()` (pydata#9689)
  Fix inadvertent deep-copying of child data in DataTree (pydata#9684)
  new blank whatsnew (pydata#9679)
  v2024.10.0 release summary (pydata#9678)
  drop the length from `numpy`'s fixed-width string dtypes (pydata#9586)
  fixing behaviour for group parameter in `open_datatree` (pydata#9666)
  Use zarr v3 dimension_names (pydata#9669)
  fix(zarr): use inplace array.resize for zarr 2 and 3 (pydata#9673)
  implement `dask` methods on `DataTree` (pydata#9670)
  support `chunks` in `open_groups` and `open_datatree` (pydata#9660)
  Compatibility for zarr-python 3.x (pydata#9552)
  Update to_dataframe doc to match current behavior (pydata#9662)
  Reduce graph size through writing indexes directly into graph for ``map_blocks`` (pydata#9658)

* main:
  Refactor out utility functions from to_zarr (pydata#9695)
  Use the same function to floatize coords in polyfit and polyval (pydata#9691)