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/src/lib.rs

@@ -0,0 +1,33 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Runtime API definition for nomination-pools pallet.
+//! Currently supports only one rpc endpoint.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use codec::Codec;
+
+sp_api::decl_runtime_apis! {
+	/// Runtime api for accessing information about nomination pools.
+	pub trait NominationPoolsApi<AccountId, Balance>
+		where AccountId: Codec, Balance: Codec
+	{
+		/// Returns the pending rewards for the member that the AccountId was given for.
+		fn pending_rewards(member: AccountId) -> Balance;
+	}
+}