Add FunctionFactoryMetadata interface for type discovery

The compiled functions implement that interface which means you can inspect
the signature of the method that created them and discover its
generic types.

spring-cloud-function-context/pom.xml

@@ -42,5 +42,11 @@
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-function-compiler</artifactId>
+			<version>${spring-cloud-function.version}</version>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 </project>