The `StompSubProtocolHandler` explicitly sets `stompCommand` header
to the `MESSAGE` value ignoring any client inputs.
In this case the message is treated as from the server and ignored on
the STOMP Broker side from the client session.
* Introduce `ClientStompEncoder` for the client side to be injected
into the `StompSubProtocolHandler` for the proper client side messages
encoding/decoding.
Override `stompCommand` header to the `SEND` value if it is `MESSAGE`
before encoding to the `byte[]` to send to the session
JIRA: https://jira.spring.io/browse/INT-4360
**Cherry-pick to 4.3.x**
Fix WebSocket test to rely on the proper client config class
and don't pick up the server config unconditionally in the test context
Conflicts:
spring-integration-websocket/src/test/java/org/springframework/integration/websocket/client/StompIntegrationTests.java
Resolved.