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/tests.rs

@@ -0,0 +1,13 @@
+use crate::{ChannelId, ParaId};
+use hex_literal::hex;
+
+const EXPECT_CHANNEL_ID: [u8; 32] =
+	hex!("c173fac324158e77fb5840738a1a541f633cbec8884c6a601c567d2b376a0539");
+
+// The Solidity equivalent code is tested in Gateway.t.sol:testDeriveChannelID
+#[test]
+fn generate_channel_id() {
+	let para_id: ParaId = 1000.into();
+	let channel_id: ChannelId = para_id.into();
+	assert_eq!(channel_id, EXPECT_CHANNEL_ID.into());
+}