WebSocket API renaming

[vietj]

Vert.x 3.x provides an inconsistent naming concerning for WebSocket, it is often spelled as Websocket. We should address this in Vert.x 4 whenever possible and provide deprecation for incorrect names.

We can fix all of them but the WebsocketVersion that would be breaking. In 3.x we provide deprecations along with correctly spelled equivalents:

• HttpServerOptions properties
  • spelling fixes
  • the fixed sub-protocols uses now List<String> instead of a coma separated string
• HttpClientOptions properties
• HttpServer handlers (websocketHandler, websocketStream)
• WebsocketRejectedException now extends the more generic UpgradeRejectedException