Adds Snowbridge to Rococo runtime (#2522)

# Description

Adds Snowbridge to the Rococo bridge hub runtime. Includes config
changes required in Rococo asset hub.

---------

Co-authored-by: Alistair Singh <alistair.singh7@gmail.com>
Co-authored-by: ron <yrong1997@gmail.com>
Co-authored-by: Vincent Geddes <vincent.geddes@hey.com>
Co-authored-by: claravanstaden <Cats 4 life!>

bridges/snowbridge/parachain/pallets/outbound-queue/runtime-api/src/lib.rs

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use frame_support::traits::tokens::Balance as BalanceT;
+use snowbridge_core::outbound::Message;
+use snowbridge_outbound_queue_merkle_tree::MerkleProof;
+
+sp_api::decl_runtime_apis! {
+	pub trait OutboundQueueApi<Balance> where Balance: BalanceT
+	{
+		/// Generate a merkle proof for a committed message identified by `leaf_index`.
+		/// The merkle root is stored in the block header as a
+		/// `\[`sp_runtime::generic::DigestItem::Other`\]`
+		fn prove_message(leaf_index: u64) -> Option<MerkleProof>;
+
+		/// Calculate the delivery fee for `message`
+		fn calculate_fee(message: Message) -> Option<Balance>;
+	}
+}