Extend the LinkML reader to CSRMatrix (sparse.yaml)

[rly]

Part of the "Read and write LinkML schema for HDMF (CSRMatrix / base.yaml)" epic. Depends on the base.yaml LinkML reader.

Extend the reader from #1489 to the constructs that CSRMatrix (sparse.yaml) adds beyond the base types: attributes, named typed datasets, dtypes (including the no-dtype AnyType case), and arrays (dims / shape via the LinkML arrays metamodel). Then verify the full test namespace (base + sparse) reads correctly.

Acceptance criteria

• The reader builds the CSRMatrix Spec from the LinkML test namespace, covering attributes, named typed datasets, dtypes (incl. AnyType for the no-dtype case), and arrays.
• Acceptance test: the Spec read from the full LinkML test namespace (base.yaml + sparse.yaml) equals the Spec HDMF loads natively from the equivalent HDMFSL namespace via the existing namespace/catalog path.
• Tests cover the added constructs at HDMF's usual coverage standard.