Removes Snowbridge parachain directory (#3186)

Removes the `bridges/snowbridge/parachain` directory and moves
everything up to under `snowbridge` directly. We are cleaning up our
local dev env after merging our crates into the polkadot-sdk.

---------

Co-authored-by: claravanstaden <Cats 4 life!>

bridges/snowbridge/primitives/core/src/inbound.rs

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <hello@snowfork.com>
+//! Types for representing inbound messages
+
+use codec::{Decode, Encode};
+use frame_support::PalletError;
+use scale_info::TypeInfo;
+use sp_core::{H160, H256};
+use sp_runtime::RuntimeDebug;
+use sp_std::vec::Vec;
+
+/// A trait for verifying inbound messages from Ethereum.
+pub trait Verifier {
+	fn verify(event: &Log, proof: &Proof) -> Result<(), VerificationError>;
+}
+
+#[derive(Clone, Encode, Decode, RuntimeDebug, PalletError, TypeInfo)]
+#[cfg_attr(feature = "std", derive(PartialEq))]
+pub enum VerificationError {
+	/// Execution header is missing
+	HeaderNotFound,
+	/// Event log was not found in the verified transaction receipt
+	LogNotFound,
+	/// Event log has an invalid format
+	InvalidLog,
+	/// Unable to verify the transaction receipt with the provided proof
+	InvalidProof,
+}
+
+pub type MessageNonce = u64;
+
+/// A bridge message from the Gateway contract on Ethereum
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Message {
+	/// Event log emitted by Gateway contract
+	pub event_log: Log,
+	/// Inclusion proof for a transaction receipt containing the event log
+	pub proof: Proof,
+}
+
+const MAX_TOPICS: usize = 4;
+
+#[derive(Clone, RuntimeDebug)]
+pub enum LogValidationError {
+	TooManyTopics,
+}
+
+/// Event log
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Log {
+	pub address: H160,
+	pub topics: Vec<H256>,
+	pub data: Vec<u8>,
+}
+
+impl Log {
+	pub fn validate(&self) -> Result<(), LogValidationError> {
+		if self.topics.len() > MAX_TOPICS {
+			return Err(LogValidationError::TooManyTopics)
+		}
+		Ok(())
+	}
+}
+
+/// Inclusion proof for a transaction receipt
+#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, TypeInfo)]
+pub struct Proof {
+	// The block hash of the block in which the receipt was included.
+	pub block_hash: H256,
+	// The index of the transaction (and receipt) within the block.
+	pub tx_index: u32,
+	// Proof keys and values (receipts tree)
+	pub data: (Vec<Vec<u8>>, Vec<Vec<u8>>),
+}