Add support for explicit FunctionRegistration

A bean of type FunctionRegistration registers the function with
user-specified name and other properties, rather than relying on the
bean name.

Alternatively, function catalog keys can be specified as a
@Qualifier, which will be used instead of the bean name if
no registration is found.

spring-cloud-function-context/pom.xml

@@ -24,6 +24,10 @@
 			<artifactId>spring-cloud-function-core</artifactId>
 			<version>${spring-cloud-function.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-web</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>com.fasterxml.jackson.core</groupId>
 			<artifactId>jackson-databind</artifactId>
@@ -33,5 +37,10 @@
 			<artifactId>spring-boot-configuration-processor</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 </project>