Dropped "Support" from the name since it not only provides support
methods but actually implements WebSocketSession.
Renamed inner classes:
WebSocketMessagePublisher -> WebSocketReceivePublisher
WebSocketMessageProcessor -> WebSocketSendProcessor
Add protected getter for sendProcessor.
Reduce scoping:
WebSocketReceivePublisher -> private
WebSocketSendProcessor -> protected
WebSocketSendProcessor#setReady -> public (class is still protected)
A few more method name alignments and Javadoc updates.
Issue: SPR-14527