Revert "Revert "override conversion rate in estimate-message-fee RPC (#1189)" (#1275)" (#1333)

This reverts commit ffd25db46c5855bcef6710b53d5ca3325ce54e56.

bridges/primitives/chain-rialto/src/lib.rs

@@ -30,7 +30,7 @@ use frame_system::limits;
 use sp_core::Hasher as HasherT;
 use sp_runtime::{
 	traits::{BlakeTwo256, Convert, IdentifyAccount, Verify},
-	MultiSignature, MultiSigner, Perbill,
+	FixedU128, MultiSignature, MultiSigner, Perbill,
 };
 use sp_std::prelude::*;
 
@@ -281,6 +281,7 @@ sp_api::decl_runtime_apis! {
 		fn estimate_message_delivery_and_dispatch_fee(
 			lane_id: LaneId,
 			payload: OutboundPayload,
+			rialto_to_this_conversion_rate: Option<FixedU128>,
 		) -> Option<OutboundMessageFee>;
 		/// Returns dispatch weight, encoded payload size and delivery+dispatch fee of all
 		/// messages in given inclusive range.