Parachains pallet benchmarks (#1436)

* added parachains pallet benchmarks

* deduplicate insertion of bridged header

* pruning weight

* fixes

* fix compilation

bridges/primitives/polkadot-core/src/parachains.rs

@@ -22,6 +22,7 @@
 //! chains. Having pallets that are referencing polkadot, would mean that there may
 //! be two versions of polkadot crates included in the runtime. Which is bad.
 
+use bp_runtime::Size;
 use frame_support::RuntimeDebug;
 use parity_scale_codec::{CompactAs, Decode, Encode, MaxEncodedLen};
 use scale_info::TypeInfo;
@@ -88,4 +89,12 @@ pub type ParaHash = crate::Hash;
 pub type ParaHasher = crate::Hasher;
 
 /// Raw storage proof of parachain heads, stored in polkadot-like chain runtime.
-pub type ParaHeadsProof = Vec<Vec<u8>>;
+#[derive(Clone, Decode, Encode, Eq, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct ParaHeadsProof(pub Vec<Vec<u8>>);
+
+impl Size for ParaHeadsProof {
+	fn size_hint(&self) -> u32 {
+		u32::try_from(self.0.iter().fold(0usize, |sum, node| sum.saturating_add(node.len())))
+			.unwrap_or(u32::MAX)
+	}
+}