Fees, weights, message delivery and dispatch (#339)

* introduce BridgedHeaderChain trait

* LaneMessageVerifier + tests

* fixed tests

* do not expose intenal functions

* cargo fmt --all + fix no_std compilation

* ByWeightDispatcher

* process queued messages from message-lane::on_initialize

* scheduled_messages_are_processed_from_on_initialize

* flush

* deal with fees + weights

* drop heavy messages on dispatch

* cargo fmt

* clippy

* fix comment

* Update primitives/message-lane/src/source_chain.rs

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

* removed messages_processed

* Update primitives/message-lane/src/source_chain.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* Update modules/message-lane/src/lib.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* remove queueing from message-lane

* also remove queueing from RPCs

* remove by-weight traces

* dispatch fee

* receiving -> delivery

* receival -> delivery

* remove extra line

* Update primitives/message-lane/src/source_chain.rs

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* cargo fmt --all

* clippy

* let dispatch_weight to be larger than actual_dispatch_weight

* post-merge fix

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

bridges/modules/message-lane/rpc/src/lib.rs

@@ -39,7 +39,7 @@ pub type MessagesProof = Bytes;
 
 /// Trie-based storage proof that the message(s) with given key(s) have been received by the bridged chain.
 /// SCALE-encoded trie nodes array `Vec<Vec<u8>>`.
-pub type MessagesReceivingProof = Bytes;
+pub type MessagesDeliveryProof = Bytes;
 
 /// Runtime adapter.
 pub trait Runtime: Send + Sync + 'static {
@@ -63,14 +63,14 @@ pub trait MessageLaneApi<BlockHash> {
 		block: Option<BlockHash>,
 	) -> FutureResult<MessagesProof>;
 
-	/// Returns proof-of-message(s) receiving.
-	#[rpc(name = "messageLane_proveMessagesReceiving")]
-	fn prove_messages_receiving(
+	/// Returns proof-of-message(s) delivery.
+	#[rpc(name = "messageLane_proveMessagesDelivery")]
+	fn prove_messages_delivery(
 		&self,
 		instance: InstanceId,
 		lane: LaneId,
 		block: Option<BlockHash>,
-	) -> FutureResult<MessagesReceivingProof>;
+	) -> FutureResult<MessagesDeliveryProof>;
 }
 
 /// Implements the MessageLaneApi trait for interacting with message lanes.
@@ -119,12 +119,12 @@ where
 		)
 	}
 
-	fn prove_messages_receiving(
+	fn prove_messages_delivery(
 		&self,
 		instance: InstanceId,
 		lane: LaneId,
 		block: Option<Block::Hash>,
-	) -> FutureResult<MessagesReceivingProof> {
+	) -> FutureResult<MessagesDeliveryProof> {
 		Box::new(
 			prove_keys_read(
 				self.backend.clone(),