The two monolithic XSD content/identity rules only satisfied the OpenAPIKit
validation idiom at the wrong granularity: no per-constraint removability,
no isolable failing/near-miss tests. Split them into 32 named rules, each
finding tagged at its origin and cached per XSDContext so the walk still
runs once per document (the #101 decision against duplicating XSD's
recursive type resolution still holds). Wired the streaming path's ID/IDREF
and identity checks through the same framework instead of calling the
validators imperatively, and added the unwrapAndLookup combinator the rule
already named as required.
Also includes the mandated repo-wide swiftformat/swiftlint pass.
cvc-identity-constraint.3 / c-fields-xpaths require an identity-constraint field to
identify a node with a simple type. The prior fix rejected a field whose selected
instance node carries element children (structural). This adds the case where the
field's DECLARED type is a complex type with non-simple content (empty or
element-only/mixed): an attributes-only element resolves to an empty-content complex
type, so its instance node is childless yet not simple-typed.
The field's target type is resolved through the schema type model (the selector
target's declared type, then the field's same-named child element in its content
model) and classified. A simple or simpleContent target, a type reached only
through a named reference, a complex field path, or an unresolvable target is left
alone, so no valid field is rejected. The resolution helpers live in a separate
extension file to keep the validator within the type-body limit.
This catches W3C XSTS idG006. XSTS invalid-instances-accepted 23 -> 22,
valid-instances-rejected held at 0.
