Use a WASM-compatible websocket library in visualiser

[mrozycki]

The websocket library currently used in the visualiser does not support wasm builds. At the time the bevy visualiser was implemented, there didn't seem to be a single websocket client library that worked both for native and wasm builds, so we will likely have to have two separate implementations using two different libraries, and compile one or the other depending on which version we're building.