Within Spring Integration's WebSocket support, a `ConcurrentWebSocketSessionDecorator`,
which buffers outbound messages if sending is slow,
is used to decorate all websocket sessions in `IntegrationWebSocketContainer`,
the standard entrypoint for using websockets with Integration.
* Expose a `ConcurrentWebSocketSessionDecorator.OverflowStrategy` option on the `IntegrationWebSocketContainer`
**Cherry-pick to `5.5.x`, `6.0.x` & `6.1.x`**
(cherry picked from commit be53593af9)
82bb183023