refactor(client): unify ws ping/pong API with the server (#1258)

* refactor(client): unify ws ping/pong api

* fix nits

* fix build

* fix wasm build

* refactor again

* Update core/Cargo.toml

* Update core/src/client/async_client/mod.rs

* Update core/src/client/async_client/mod.rs

* fix build again

* Update core/src/client/async_client/mod.rs

* fix grumbles

* fix fmt nit

* emit error when ping/pong terminates conn