frame/utils: introduce substrate-rpc-client crate for RPC utils (#12212)

* hack together a PoC

* Update utils/frame/rpc-utils/Cargo.toml

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update utils/frame/rpc-utils/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* rpc_utils -> substrate_rpc_client

* try runtime: remove keep connection

* make CI happy

* cargo fmt

* fix ci

* update lock file

* fix

* fix

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: kianenigma <kian@parity.io>

substrate/utils/frame/rpc/client/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "substrate-rpc-client"
+version = "0.10.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "Apache-2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+description = "Shared JSON-RPC client"
+readme = "README.md"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+jsonrpsee = { version = "0.15.1", features = ["ws-client"] }
+sc-rpc-api = { version = "0.10.0-dev", path = "../../../../client/rpc-api" }
+async-trait = "0.1.57"
+serde = "1"
+sp-runtime = { version = "6.0.0", path = "../../../../primitives/runtime" }
+log = "0.4"
+
+[dev-dependencies]
+tokio = { version = "1.17.0", features = ["macros", "rt-multi-thread", "sync"] }
+sp-core = { path = "../../../../primitives/core" }