* draft: client trait sketch...

* use async_trait instead of `Box<Future>`

* refactor client trait

* [types]: shared client types.

* integrate with `jsonrpsee_proc_macros::rpc_api`

* Update proc-macros/src/lib.rs

* integrate with proc macros

* fix: hacky support for generic types in proc macro

* fix: make the examples work.

* trait: error associated type

* Update types/src/traits.rs

* client trait: make object safe.

Make the trait usable as a trait object i.e, `Box<dyn Trait>`

* client trait: remove `Self::Sized`

* add tests for proc macros.

* fix build

* fmt

* [client trait]: remove unused associated error typ

* [proc macros]: separate enum variant each return_t

* add tracking issue to `TODO`

* doc(client trait): improve documentation.

* separate trait for subscribing client

* add documentation

* proc macros: remove debug impl

* fix compile warns

* address grumbles: remove fn process_response

* Update types/src/client.rs

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

* Update types/src/client.rs

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

* Update types/src/client.rs

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

* Update types/src/client.rs

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

* Update types/src/client.rs

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

* remove old proc macro tests

* address grumbles: shorter lines

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

* update http example

* ungeneric crate

* update dependencies

* [client]: add WebSocket client again.

* [deps]: remove needless dev dependencies

* nits: forgot to commit new files

* [ws client]: `send_text` instead of `send_binary`

This is temporary fix to work with the `server` which assumes that
`WebSocket` resonses are `text`

* chore: add a bunch of more logging

* [ws]: port tests but some are failing.

* chore: fmt

* [server API]: expose `fn local_addr` as public API.

* [tests]: make them less ugly by using `127.0.0.1:0`

* fix: a bunch of compiler warnings.

* [api]: uniform naming, `bind -> new` in transport.

* [websocket server]: reply when deserial fails

When the server receives an request with invalid JSON
`-32700, Parse error shall be returned`

* chore: fmt

* [tests]: fix remaining tests

* [websocket server]: support `binary` and `text`

* [ws server]: fix bug in subscription response.

`.await` was missing in ...