Fix delivery transaction estimation used by rational relayer (#1109)

* fix delivery transaction estimation in greedy relayer

* fixed typo

* improve logging

* improve logging

* fmt

* fix compilation

* fmt

* Update relays/lib-substrate-relay/src/messages_target.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* review

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

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

@@ -22,6 +22,7 @@
 
 use bp_messages::{LaneId, MessageDetails, MessageNonce, UnrewardedRelayersState};
 use bp_runtime::Chain;
+use frame_support::weights::{WeightToFeeCoefficient, WeightToFeeCoefficients, WeightToFeePolynomial};
 use sp_std::prelude::*;
 use sp_version::RuntimeVersion;
 
@@ -30,6 +31,24 @@ pub use bp_polkadot_core::*;
 /// Westend Chain
 pub type Westend = PolkadotLike;
 
+// NOTE: This needs to be kept up to date with the Westend runtime found in the Polkadot repo.
+pub struct WeightToFee;
+impl WeightToFeePolynomial for WeightToFee {
+	type Balance = Balance;
+	fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
+		const CENTS: Balance = 1_000_000_000_000 / 1_000;
+		// in Westend, extrinsic base weight (smallest non-zero weight) is mapped to 1/10 CENT:
+		let p = CENTS;
+		let q = 10 * Balance::from(ExtrinsicBaseWeight::get());
+		smallvec::smallvec![WeightToFeeCoefficient {
+			degree: 1,
+			negative: false,
+			coeff_frac: Perbill::from_rational(p % q, q),
+			coeff_integer: p / q,
+		}]
+	}
+}
+
 pub type UncheckedExtrinsic = bp_polkadot_core::UncheckedExtrinsic<Call>;
 
 // NOTE: This needs to be kept up to date with the Westend runtime found in the Polkadot repo.