Add MockExchangeFunction getResponse

This allows setting up the mock

Issue: gh-5386

oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/web/reactive/function/client/MockExchangeFunction.java

@@ -43,6 +43,9 @@ public class MockExchangeFunction implements ExchangeFunction {
 	public List<ClientRequest> getRequests() {
 		return this.requests;
 	}
+
+	public ClientResponse getResponse() {
+		return this.response;
 	}
 
 	@Override