Support for ircv3 websocket

[d3xt3r01]

Feature description

Unrealircd supports websocket (https://www.unrealircd.org/docs/WebSocket_support)
Some servers use this to completely hide behind cloudflare for flood protection with no direct connection available.
Would be nice to be able to connect via WS from weechat directly and not use the webinterface.

[d3xt3r01]

Another useful thing I imagine this would be used when behind a firewalled network that still allows web traffic.
Of course a proxy could probably be used but this would be easier.