* feat(http client): batch requests

* fix(http batch request): request in any order.

* Update src/types/jsonrpc/id.rs

* tests(batch out-of-order): make it less confusing.

* fix nit: `cloned` -> `copied`

* fix bad merge

* [client]: batch request generic response

* wait with impl

* [ws client]: add template for batch requests

* remove jsonvalue

* naive impl

* fix make it work,

The implemenation is quite inefficient because the responses might be unordered.
Currently, a "digest" of a BTreeSet is stored to sort the requestIDs
and don't have to try all combinations of requestIDs in the response.

* fix nits

* error handling

* fix nits

* more nits

* use error msg pattern

* add batch requests to client trait

Keep it simple by require `Vec<(Method, Params)>` could be improved.

* address review comments: use swap_remove

Replace read values with `Vec::swap_remove` instead inserting dummy value.
The reason is that `Vec::remove` is O(n)

* address review grumbles: batch trait bound Default

* don't be clever

* [http client]: faster lookup for batch request.

* fix: distguish request_id and batch_id

* thanks clippy

* fix: clarify bad response with a separate error

* fix tests

* add issue link to todo

* Update types/src/error.rs

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

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

* 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]>