[ws client]: background error reporting to frontend (#234)

* implement background error reporting

* introduce new error variant

* [ws client]: remove `Clone`

Breaking change which removes the `Clone` on the `WsClient`.
It's better that users explictly makes it clone if that's desired,
for example by putting it in `Arc<Mutex>`.

* fix build

* Update ws-client/src/client.rs

* remove unused arc

* Update ws-client/src/client.rs

Co-authored-by: David <[email protected]>

* Update ws-client/src/client.rs

Co-authored-by: David <[email protected]>

* Update ws-client/src/client.rs

Co-authored-by: David <[email protected]>

* fix rustdoc link

Co-authored-by: David <[email protected]>