XCM revamp (#2836)

* Remove unused relaying XCM

* Aggregate HRMP (XCMP/HMP) messages. Payloads for spambot.

* Revert lock

* Fix

* Broken example

* Introduce fee payment mechanics into XCM.

* Weight limitations on XCM execution

* Mock environment for tests and the first test

* Tests for XCM and a few refactors.

* Remove code that's not ready

* Fix for an XCM and an additional test

* Query response system

* XCMP message dispatch system reimagining

- Moved most of the logic into xcm-handler pallet
- Altered the outgoing XCMP API from push to pull
- Changed underlying outgoing queue data structures to avoid multi-page read/writes
- Introduced queuing for incoming messages
- Introduced signal messages as a flow-control sub-stream
- Introduced flow-control with basic threshold back-pressure
- Introduced overall weight limitation on messages executed
- Additonal alterations to XCM APIs for the new system

* Some build fixes

* Remove the Encode bounds sprayed around

* More faff

* Fix bounds amek use latest scale codec.

* remove println

* fixes

* Fix XcmExecutor Tests

* Fix XCM bounds using derivative crate

* Refactor names of XcmGeneric &c into Xcm

* Repot the xcm-executor into xcm-builder

* Docs

* Docs

* Fixes

* Update xcm/src/lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Fixes

* Docs

* Update runtime/parachains/src/ump.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Docs

* Fixes

* Fixes

* Fixes

* Docs

* Fixes

* Fixes

* Introduce transfer_asset specialisation.

* Fixes

* Fixes

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

polkadot/xcm/xcm-builder/src/origin_conversion.rs

@@ -17,7 +17,7 @@
 use sp_std::marker::PhantomData;
 use frame_support::traits::{Get, OriginTrait};
 use xcm::v0::{MultiLocation, OriginKind, NetworkId, Junction};
-use xcm_executor::traits::{LocationConversion, ConvertOrigin};
+use xcm_executor::traits::{Convert, ConvertOrigin};
 use polkadot_parachain::primitives::IsSystem;
 
 /// Sovereign accounts use the system's `Signed` origin with an account ID derived from the
@@ -26,12 +26,12 @@ pub struct SovereignSignedViaLocation<LocationConverter, Origin>(
 	PhantomData<(LocationConverter, Origin)>
 );
 impl<
-	LocationConverter: LocationConversion<Origin::AccountId>,
+	LocationConverter: Convert<MultiLocation, Origin::AccountId>,
 	Origin: OriginTrait,
-> ConvertOrigin<Origin> for SovereignSignedViaLocation<LocationConverter, Origin> {
+> ConvertOrigin<Origin> for SovereignSignedViaLocation<LocationConverter, Origin> where Origin::AccountId: Clone {
 	fn convert_origin(origin: MultiLocation, kind: OriginKind) -> Result<Origin, MultiLocation> {
 		if let OriginKind::SovereignAccount = kind {
-			let location = LocationConverter::from_location(&origin).ok_or(origin)?;
+			let location = LocationConverter::convert(origin)?;
 			Ok(Origin::signed(location).into())
 		} else {
 			Err(origin)