Make MTRDecodeAttributeValue support global attributes in custom clusters. (#29022)

For global attributes we know the schema even if the cluster is custom.

Author: bzbarsky-apple

src/darwin/Framework/CHIP/templates/MTRAttributeTLVValueDecoder-src.zapt

@@ -12,17 +12,56 @@
 #include <app-common/zap-generated/ids/Attributes.h>
 #include <app-common/zap-generated/ids/Clusters.h>
 #include <lib/support/TypeTraits.h>
+#include <lib/core/DataModelTypes.h>
 
 using namespace chip;
 using namespace chip::app;
 
+static id _Nullable DecodeGlobalAttributeValue(AttributeId aAttributeId, TLV::TLVReader & aReader, CHIP_ERROR * aError)
+{
+    using namespace Clusters::Globals;
+    switch (aAttributeId) {
+        {{#zcl_attributes_server removeKeys='isOptional'}}
+        {{#unless clusterRef}}
+        {{#if (isSupported "" globalAttribute=(asUpperCamelCase name preserveAcronyms=true))}}
+        {{#if (isProvisional "" globalAttribute=(asUpperCamelCase name preserveAcronyms=true))}}
+        #if MTR_ENABLE_PROVISIONAL
+        {{/if}}
+        case Attributes::{{asUpperCamelCase name}}::Id: {
+            using TypeInfo = Attributes::{{asUpperCamelCase name}}::TypeInfo;
+            TypeInfo::DecodableType cppValue;
+            *aError = DataModel::Decode(aReader, cppValue);
+            if (*aError != CHIP_NO_ERROR)
+            {
+                return nil;
+            }
+            {{asObjectiveCType type ""}} value;
+            {{>decode_value target="value" source="cppValue" cluster="" errorCode="*aError = err; return nil;" depth=0}}
+            return value;
+        }
+        {{#if (isProvisional "" globalAttribute=(asUpperCamelCase name preserveAcronyms=true))}}
+        #endif // MTR_ENABLE_PROVISIONAL
+        {{/if}}
+        {{/if}}
+        {{/unless}}
+        {{/zcl_attributes_server}}
+        default: {
+            break;
+        }
+    }
+
+    *aError = CHIP_ERROR_IM_MALFORMED_ATTRIBUTE_PATH_IB;
+    return nil;
+}
+
 {{#zcl_clusters}}
 {{#if (isSupported (asUpperCamelCase name preserveAcronyms=true))}}
 static id _Nullable DecodeAttributeValueFor{{asUpperCamelCase name preserveAcronyms=true}}Cluster(AttributeId aAttributeId, TLV::TLVReader & aReader, CHIP_ERROR * aError)
 {
     using namespace Clusters::{{asUpperCamelCase name}};
     switch (aAttributeId) {
         {{#zcl_attributes_server removeKeys='isOptional'}}
+        {{#if clusterRef}}
         {{#if (isSupported (asUpperCamelCase ../name preserveAcronyms=true) attribute=(asUpperCamelCase name preserveAcronyms=true))}}
         {{#if (isProvisional (asUpperCamelCase ../name preserveAcronyms=true) attribute=(asUpperCamelCase name preserveAcronyms=true))}}
         #if MTR_ENABLE_PROVISIONAL
@@ -43,6 +82,7 @@ static id _Nullable DecodeAttributeValueFor{{asUpperCamelCase name preserveAcron
         #endif // MTR_ENABLE_PROVISIONAL
         {{/if}}
         {{/if}}
+        {{/if}}
         {{/zcl_attributes_server}}
         default: {
             break;
@@ -57,6 +97,10 @@ static id _Nullable DecodeAttributeValueFor{{asUpperCamelCase name preserveAcron
 
 id _Nullable MTRDecodeAttributeValue(const ConcreteAttributePath & aPath, TLV::TLVReader & aReader, CHIP_ERROR * aError)
 {
+    if (IsGlobalAttribute(aPath.mAttributeId)) {
+        return DecodeGlobalAttributeValue(aPath.mAttributeId, aReader, aError);
+    }
+
     switch (aPath.mClusterId) {
         {{#zcl_clusters}}
         {{#if (isSupported (asUpperCamelCase name preserveAcronyms=true))}}