Switch parachain interface to new runtime_interface macro (#665)

* Make use of `runtime_interface` for parachain externalities

This also changes the encoding of the `ValidationResult` return value to
match the default encoding used in Substrate.

* Fix compilation for web

* Update `Cargo.lock`

* Include feedback

* Move proc macro

* Update parachain/src/lib.rs

Co-Authored-By: Robert Habermeier <rphmeier@gmail.com>

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

polkadot/primitives/src/parachain.rs

@@ -35,7 +35,7 @@ use application_crypto::KeyTypeId;
 use trie::TrieConfiguration;
 
 pub use polkadot_parachain::{
-	Id, ParachainDispatchOrigin, LOWEST_USER_ID, UpwardMessage,
+	Id, ParachainDispatchOrigin, LOWEST_USER_ID, UpwardMessage, TargetedMessage,
 };
 
 /// The key type ID for a collator key.
@@ -164,36 +164,6 @@ pub struct DutyRoster {
 	pub validator_duty: Vec<Chain>,
 }
 
-/// A message targeted to a specific parachain.
-#[derive(Clone, PartialEq, Eq, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug))]
-#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
-#[cfg_attr(feature = "std", serde(deny_unknown_fields))]
-pub struct TargetedMessage {
-	/// The target parachain.
-	pub target: Id,
-	/// The message data.
-	pub data: Vec<u8>,
-}
-
-impl AsRef<[u8]> for TargetedMessage {
-	fn as_ref(&self) -> &[u8] {
-		&self.data[..]
-	}
-}
-
-impl PartialOrd for TargetedMessage {
-	fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-		Some(self.target.cmp(&other.target))
-	}
-}
-
-impl Ord for TargetedMessage {
-	fn cmp(&self, other: &Self) -> Ordering {
-		self.target.cmp(&other.target)
-	}
-}
-
 /// Outgoing message data for a parachain candidate.
 ///
 /// This is data produced by evaluating the candidate. It contains