[ws-client] Make wasm compatible

[athei]

There is #227 which covers making the http client wasm compatible. However, I think the ws client is much more important because it is the only one allowing subscriptions. It would allow for creating web frontends written in Rust through subxt.

With wasm compatible I mean "runs in a browser". This means making use of web-sys to interact with the browser.

[niklasad1]

However, I think the ws client is much more important because it is the only one allowing subscription

yeah, indeed.

It's been a while since I looked at the https://github.com/najamelan/ws_stream_wasm but it won't work because the "async/ws" client assumes it assumes that transport can be split into a sender and receiver because we are using them in different tasks (but not sure if it works in WASM anyway)

However, https://github.com/nash-io/nash-ws looks quite promising. I think it should be straight-forward to port over.

[athei]

Maybe its worthwhile to use web-sys directly. This crate you mentioned looks kind of abandoned.

[niklasad1]

Closed by #648