feat(metadata): resource and operation level itemUriTemplate

[Amoifr]

Implements the plan laid out in #8075 (comment) (resource + operation itemUriTemplate), closes #8075.

When an item operation has a custom uriTemplate (new Patch(uriTemplate: '/purchases/{id}/billing-address')), the response @id reuses that URI instead of the canonical one. itemUriTemplate existed only on Post and GetCollection; this lifts it up:

• Op-level: itemUriTemplate moves to HttpOperation (with getItemUriTemplate()/withItemUriTemplate()), so Get, Patch and Put accept it; Post and GetCollection keep their signature and delegate.
• Resource-level: ApiResource gains itemUriTemplate as a DRY default; the propagation to operations is automatic through the generic cascadeFromResource()/copyFrom() mechanism, with op-level precedence (op ?? resource ?? null).
• IriConverter (Symfony and Laravel; Mcp delegates): when the resolved operation is a non-collection HttpOperation carrying an itemUriTemplate, the target operation is resolved through OperationMetadataFactory::create(). The block is skipped when $context['item_uri_template'] was already resolved at the top of the method, which avoids a double resolution through the cascaded template of the target operation (caught by the functional test on op-level precedence).
• Extractors: XML + YAML support itemUriTemplate at the resource level, and the op-level whitelist accepts Get, Patch and Put (it threw before); XSD updated.
• Serializer context: nothing to change, SerializerContextBuilder, OperationContextTrait and the JSON:API ItemNormalizer already feed item_uri_template through method_exists($operation, 'getItemUriTemplate').

Additive, no behavior change when the option is unset. Covered by a unit test on the Symfony IriConverter and a functional test (CanonicalIriTest) asserting the canonical @id for a PATCH with a custom URI, both with the resource-level default and with an op-level override taking precedence. The exhaustive ResourceMetadataCompatibilityTest covers the new resource property through the XML/YAML adapters.