…in order to minimize pipeline
Motivation:
Handling of `WebSocketCloseFrame` is part of websocket protocol, so it's logical to put it within the `WebSocketProtocolHandler`. Also, removal of `WebSocketCloseFrameHandler` will decrease the channel pipeline.
Modification:
- `WebSocketCloseFrameHandler` code merged into `WebSocketProtocolHandler`. `WebSocketCloseFrameHandler` not added to the pipeline anymore
- Added additional constructor to `WebSocketProtocolHandler`
- `WebSocketProtocolHandler` now implements `ChannelOutboundHandler` and implements basic methods from it
Result:
`WebSocketCloseFrameHandler` is no longer used.
Fixes https://github.com/netty/netty/issues/9944