feat: add support for querying the maximum number of supported dimensions

Closes: data-apis#694

Author: kgryte

Diff for: src/array_api_stubs/_draft/_types.py

@@ -140,5 +140,10 @@ def dtypes(
     total=False,
 )
 Capabilities = TypedDict(
-    "Capabilities", {"boolean indexing": bool, "data-dependent shapes": bool}
+    "Capabilities",
+    {
+        "boolean indexing": bool,
+        "data-dependent shapes": bool,
+        "max rank": Optional[int],
+    },
 )

Diff for: src/array_api_stubs/_draft/info.py

@@ -56,6 +56,7 @@ def capabilities() -> Capabilities:
 
     -   `"boolean indexing"`: boolean indicating whether an array library supports boolean indexing. If a conforming implementation fully supports boolean indexing in compliance with this specification (see :ref:`indexing`), the corresponding dictionary value must be ``True``; otherwise, the value must be ``False``.
     -   `"data-dependent shapes"`: boolean indicating whether an array library supports data-dependent output shapes. If a conforming implementation fully supports all APIs included in this specification (excluding boolean indexing) which have data-dependent output shapes, as explicitly demarcated throughout the specification, the corresponding dictionary value must be ``True``; otherwise, the value must be ``False``.
+    -   `"max rank"`: maximum number of supported dimensions. If a conforming implementation supports arrays having an arbitrary number of dimensions (potentially infinite), the corresponding dictionary value must be ``None``; otherwise, the value must be a finite integer.
 
     Returns
     -------