Fix FunctionTypeUtils for FactoryBean

The function bean can be declared as a `FactoryBean`,
for example with Spring Integration's `GatewayProxyFactoryBean`.
See `LogConsumerConfiguration` in Spring Functions Catalog project.

* Fix `FunctionTypeUtils` to react to the `ParameterizedType`
and check its assignments against `Factory` bean.
Then resolves its generic to the proper target function type.
* Add `BeanFactoryAwareFunctionRegistryTests.functionFromFactoryBeanIsProperlyResolved()`
to verify that `FactoryBean<Function<?, ?>>` is resolved properly

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/FunctionTypeUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2022 the original author or authors.
+ * Copyright 2019-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -78,6 +78,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Oleg Zhurakousky
  * @author Andrey Shlykov
+ * @author Artem Bilan
  *
  * @since 3.0
  */
@@ -444,6 +445,12 @@ public final class FunctionTypeUtils {
 				}
 			}
 		}
+		else if (type instanceof ParameterizedType) {
+			ResolvableType resolvableType = ResolvableType.forType(type);
+			if (FactoryBean.class.isAssignableFrom(resolvableType.toClass())) {
+				return resolvableType.getGeneric(0).getType();
+			}
+		}
 		return type;
 	}