Migrate to Tomcat WebSocket client

Move samples and tests from Jetty websocket client to Tomcat since the
upcoming Jetty release contains a bug in `JsrSession`
(https://github.com/eclipse/jetty.project/issues/1202).

See gh-7599

spring-boot-devtools/pom.xml

@@ -117,6 +117,16 @@
 			<artifactId>spring-webmvc</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-websocket</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.apache.tomcat.embed</groupId>
+			<artifactId>tomcat-embed-websocket</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.tomcat.embed</groupId>
 			<artifactId>tomcat-embed-core</artifactId>