[proc macros]: can't define trait without client feature which brings lots of unecessary deps.

[niklasad1]

I noticed after the refactoring of the core crate and if I want to do:

use jsonrpsee::{core::RpcResult, proc_macros::rpc};

#[rpc(client, server, namespace = "myapi")]
pub trait MyApi {
	#[method(name = "submitBytes")]
	async fn submit_bytes(&self,  bytes: Vec<u8>) -> RpcResult<()>;
}

To get the client traits required then one must enable the client feature which brings in a bunch of dependencies from http-client and ws-client.

Maybe we could enable "jsonrpsee-core/client" in the macros feature it's really light weight just a few of our own types.

[dvdplm]

Makes sense to me.

[niklasad1]

Closed by #656