pallet-xcm: Deprecate execute and send in favor of execute_blob and send_blob (#3749)

`execute` and `send` try to decode the xcm in the parameters before
reaching the filter line.
The new extrinsics decode only after the filter line.
These should be used instead of the old ones.

## TODO
- [x] Tests
- [x] Generate weights
- [x] Deprecation issue ->
https://github.com/paritytech/polkadot-sdk/issues/3771
- [x] PRDoc
- [x] Handle error in pallet-contracts

This would make writing XCMs in PJS Apps more difficult, but here's the
fix for that: https://github.com/polkadot-js/apps/pull/10350.
Already deployed! https://polkadot.js.org/apps/#/utilities/xcm

Supersedes https://github.com/paritytech/polkadot-sdk/pull/1798/

---------

Co-authored-by: PG Herveou <pgherveou@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

cumulus/parachains/integration-tests/emulated/tests/bridges/bridge-hub-westend/Cargo.toml

@@ -11,6 +11,7 @@ publish = false
 workspace = true
 
 [dependencies]
+codec = { package = "parity-scale-codec", version = "3.6.0" }
 
 # Substrate
 frame-support = { path = "../../../../../../../substrate/frame/support", default-features = false }

cumulus/parachains/integration-tests/emulated/tests/bridges/bridge-hub-westend/src/tests/send_xcm.rs

@@ -14,6 +14,7 @@
 // limitations under the License.
 
 use crate::tests::*;
+use codec::Encode;
 
 #[test]
 fn send_xcm_from_westend_relay_to_rococo_asset_hub_should_fail_on_not_applicable() {
@@ -26,7 +27,7 @@ fn send_xcm_from_westend_relay_to_rococo_asset_hub_should_fail_on_not_applicable
 
 	let remote_xcm = Xcm(vec![ClearOrigin]);
 
-	let xcm = VersionedXcm::from(Xcm(vec![
+	let xcm = VersionedXcm::from(Xcm::<()>(vec![
 		UnpaidExecution { weight_limit, check_origin },
 		ExportMessage {
 			network: RococoId,
@@ -38,10 +39,10 @@ fn send_xcm_from_westend_relay_to_rococo_asset_hub_should_fail_on_not_applicable
 	// Westend Global Consensus
 	// Send XCM message from Relay Chain to Bridge Hub source Parachain
 	Westend::execute_with(|| {
-		assert_ok!(<Westend as WestendPallet>::XcmPallet::send(
+		assert_ok!(<Westend as WestendPallet>::XcmPallet::send_blob(
 			sudo_origin,
 			bx!(destination),
-			bx!(xcm),
+			xcm.encode().try_into().unwrap(),
 		));
 
 		type RuntimeEvent = <Westend as Chain>::RuntimeEvent;