graph::ChainApi and graph::Pool reexport (paritytech#9726)

* `graph::ChainApi` and `graph::Pool` reexport

* Redundant import cleanup

(cherry picked from commit b391b82)

client/transaction-pool/src/lib.rs

@@ -44,7 +44,7 @@ use futures::{
 	future::{self, ready},
 	prelude::*,
 };
-pub use graph::{Options, Transaction};
+pub use graph::{ChainApi, Options, Pool, Transaction};
 use parking_lot::Mutex;
 use std::{
 	collections::{HashMap, HashSet},
@@ -451,7 +451,7 @@ where
 		at: &BlockId<Self::Block>,
 		xt: sc_transaction_pool_api::LocalTransactionFor<Self>,
 	) -> Result<Self::Hash, Self::Error> {
-		use graph::{ChainApi, ValidatedTransaction};
+		use graph::ValidatedTransaction;
 		use sp_runtime::{
 			traits::SaturatedConversion, transaction_validity::TransactionValidityError,
 		};