create_array creates explicit groups

[d-v-b]

Fixes #2794.

• init_array used to return a metadata object, and it would only create a single metadata document (the source of the bug reported in zarr v3 still generates implicit groups #2794). init_array is modified to create parent groups as needed, and it returns an AsyncArray instance, and accordingly it now takes a config parameter.

A few off-target changes of note, that were necessary to make the above change smoother:

• The dict form of the ArrayConfig was renamed from ArrayConfigLike to ArrayConfigParams, and the name ArrayConfigLike is now used for the union of ArrayConfig | ArrayConfigParams.
• Config parsing now happens in AsyncArray.__init__, instead of higher up, since we were already accepting None in that function this is a simplifying change.
• create_array tests are grouped in a test class. I combined some redundant tests.

[d-v-b]

i can build the docs locally, so I'm confused why the build in ci is failing. Any ideas @dstansby ?

[dstansby]

i can build the docs locally, so I'm confused why the build in ci is failing. Any ideas @dstansby ?

Have you looked at the difference between the build here, and the last readthedocs build that passed to see if there's any obvious differences that could be causing the issue?

[d-v-b]

it looks like in the last 20 hours all docs builds for PRs against main have failed with warnings like

[AutoAPI] Reading files... [  2%] /home/docs/checkouts/readthedocs.org/user_builds/zarr/checkouts/2795/src/zarr/_version.py
WARNING: Unable to read file: /home/docs/checkouts/readthedocs.org/user_builds/zarr/checkouts/2795/src/zarr/_version.py [autoapi.not_readable]
[AutoAPI] Reading files... [  3%] /home/docs/checkouts/readthedocs.org/user_builds/zarr/checkouts/2795/src/zarr/creation.py
WARNING: Unable to read file: /home/docs/checkouts/readthedocs.org/user_builds/zarr/checkouts/2795/src/zarr/creation.py [autoapi.not_readable]

the only difference I can see between this and the successful builds is the lack of warnings, and thus the lack of failure. That's not super informative to me unfortunately.

[dstansby]

Are all the dependencies being installed the same between a passing/failing build too?

[d-v-b]

Are all the dependencies being installed the same between a passing/failing build too?

as far as I can tell there are no differences in the docs build process, but it's possible that I missed something.

[d-v-b]

since #2796 is failing for the same reasons, I feel confident that nothing in this PR is actually causing the docs build problems.