Add runtime hints for AbstractHandshakeHandler

[mhalbritter]

When running the native-image from the spring-native sample websocket on the sb-3.0.x branch, i get the following exception:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'stompWebSocketHandlerMapping': Instantiation of supplied bean failed
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainInstanceFromSupplier(AbstractAutowireCapableBeanFactory.java:1234) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainFromSupplier(AbstractAutowireCapableBeanFactory.java:1209) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1156) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:566) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:526) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:930) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:926) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:592) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146) ~[websocket:3.0.0-SNAPSHOT]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:735) ~[websocket:3.0.0-SNAPSHOT]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:431) ~[websocket:3.0.0-SNAPSHOT]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:310) ~[websocket:3.0.0-SNAPSHOT]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1307) ~[websocket:3.0.0-SNAPSHOT]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1296) ~[websocket:3.0.0-SNAPSHOT]
	at com.example.websocket.WebsocketApplication.main(WebsocketApplication.java:20) ~[websocket:0.0.1-SNAPSHOT]
Caused by: java.lang.IllegalStateException: Failed to instantiate RequestUpgradeStrategy: org.springframework.web.socket.server.standard.TomcatRequestUpgradeStrategy
	at org.springframework.web.socket.server.support.AbstractHandshakeHandler.initRequestUpgradeStrategy(AbstractHandshakeHandler.java:160) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.web.socket.server.support.AbstractHandshakeHandler.<init>(AbstractHandshakeHandler.java:118) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.web.socket.server.support.DefaultHandshakeHandler.<init>(DefaultHandshakeHandler.java:35) ~[na:na]
	at org.springframework.web.socket.server.support.WebSocketHttpRequestHandler.<init>(WebSocketHttpRequestHandler.java:73) ~[na:na]
	at org.springframework.web.socket.config.annotation.WebMvcStompWebSocketEndpointRegistration.getMappings(WebMvcStompWebSocketEndpointRegistration.java:160) ~[na:na]
	at org.springframework.web.socket.config.annotation.WebMvcStompEndpointRegistry.getHandlerMapping(WebMvcStompEndpointRegistry.java:155) ~[na:na]
	at org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurationSupport.stompWebSocketHandlerMapping(WebSocketMessageBrokerConfigurationSupport.java:92) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurationSupport__BeanDefinitions.lambda$getStompWebSocketHandlerMappingInstance$0(WebSocketMessageBrokerConfigurationSupport__BeanDefinitions.java:38) ~[na:na]
	at org.springframework.util.function.ThrowingFunction.apply(ThrowingFunction.java:63) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.util.function.ThrowingFunction.apply(ThrowingFunction.java:51) ~[websocket:6.0.0-SNAPSHOT]
	at org.springframework.beans.factory.aot.AutowiredInstantiationArgumentsResolver.resolve(AutowiredInstantiationArgumentsResolver.java:156) ~[na:na]
	at org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurationSupport__BeanDefinitions.getStompWebSocketHandlerMappingInstance(WebSocketMessageBrokerConfigurationSupport__BeanDefinitions.java:38) ~[na:na]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainInstanceFromSupplier(AbstractAutowireCapableBeanFactory.java:1223) ~[websocket:6.0.0-SNAPSHOT]
	... 18 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.web.socket.server.standard.TomcatRequestUpgradeStrategy
	at java.lang.Class.forName(DynamicHub.java:1121) ~[websocket:na]
	at org.springframework.util.ClassUtils.forName(ClassUtils.java:284) ~[na:na]
	at org.springframework.web.socket.server.support.AbstractHandshakeHandler.initRequestUpgradeStrategy(AbstractHandshakeHandler.java:156) ~[websocket:6.0.0-SNAPSHOT]
	... 30 common frames omitted