Spring Expose the proxyPing property for client or server WebSocket with Reactor Netty

See https://github.com/reactor/reactor-netty/pull/945#issuecomment-571640355 for @violetagg's suggested places framework needs changing.

This is reactor-netty 9.3.x and 1.0.x so framework 5.2.x and 5.3.x respectively IIRC.

This is to support spring cloud gateway

Comment From: rstoyanchev

@spencergibb this will have to be a configurable property on ReactorNettyRequestUpgradeStrategy and also on ReactorNettyWebSocketClient, similar to the maxFramePayloadLength that's already in both.

Comment From: JacobASeverson

Hi folks, I've opened https://github.com/spring-projects/spring-framework/pull/24367 to address this.