Add auto-configuration for Observations in Spring-WS

I have added support for Observations in Spring-WS, and the next step would be to add auto-configuration for the ObservationInterceptors.

As far as I can tell, it could perhaps be implemented in the module spring-boot-actuator-autoconfigure under the package
org.springframework.boot.actuate.autoconfigure.observation.webservice.client or org.springframework.boot.actuate.autoconfigure.observation.webservice.server

For the WebServiceTemplate, the interceptor could probably be added by implementing a WebServiceTemplateCustomizer that is added to the context.
Condition for activating the configuration class could perhaps be @ConditionalOnBean(ObservationRegistry.class)

For the server Endpoints, the interceptor could probably be added in the addInterceptors-callback in the WsConfigurerAdapter.
Condition for activating the configuration class could perhaps be @ConditionalOnBean(ObservationRegistry.class)

The new Observation was merged in https://github.com/spring-projects/spring-ws/pull/1438 for the issue
https://github.com/spring-projects/spring-ws/issues/1094

This is also related to https://github.com/spring-projects/spring-boot/issues/15390

Start in spring-boot-actuator-autoconfigure and review the proposed webservice.client and webservice.server packages, along with WebServiceTemplateCustomizer and the WsConfigurerAdapter addInterceptors callback. Use the linked Spring-WS observation work as context. Done means ObservationInterceptors are auto-configured for client and server endpoints when an ObservationRegistry is present.