Rpc for pending rewards (#11831)

* rpc pending rewards

* commit

* remove unused imports

* fix

* fix

* fmt

* fix

* fmt

* fix

* docs

* docs & formatting

* better formatting

* temporary fix

* error handling

* fix?

* fmt

* use to_string

* fmt

* fixed error handling

* fix

* rpc added to client

* Update Cargo.toml

* Update Cargo.toml

* fix wrong reward counter

* expose function

* move implementation

* docs

* docs

* docs

* Update lib.rs

* Update lib.rs

* unexpose functions

* unused dependency

* update Cargo.lock

* Update frame/nomination-pools/src/lib.rs

* Update lib.rs

* Update lib.rs

* Update frame/nomination-pools/rpc/runtime-api/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* remove rpc

* remove rpc directory

* final fix

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

substrate/frame/nomination-pools/runtime-api/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "pallet-nomination-pools-runtime-api"
+version = "1.0.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "Apache-2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+description = "Runtime API for nomination-pools FRAME pallet"
+readme = "README.md"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive"] }
+sp-api = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/api" }
+sp-std = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/std" }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+	"sp-api/std",
+	"sp-std/std",
+]