[FEA]: Add a consistency check for cuda.core.__all__ vs cuda_core/docs/source/api.rst

[rwgk]

xref: #2300 (review)

Copy-pasting the relevant part for easy referrence:

Add a follow-on docs/API consistency test that compares the public symbols in cuda.core.__all__ against the public entries in cuda_core/docs/source/api.rst, with deliberate exceptions for submodule namespaces and returned-helper/private API docs.

It should parse the Sphinx autosummary and data entries, then account for known surfaces such as cuda.core.graph, cuda.core.texture, cuda.core.utils, cuda.core.checkpoint, and entries intentionally documented in api_private.rst. The useful failure mode is: “this symbol is public by __all__ but missing from public docs” or “this symbol is documented as public but not exported by __all__.”