Implement presumed_origin

Before we yield a block for scanning, we save all of the contained script
public keys. Then, when we want the address credited for creating an output,
we read the script public key of the spent output from the database.

Fixes #559.

processor/bitcoin/src/main.rs

@@ -18,6 +18,10 @@ mod block;
 mod rpc;
 mod scheduler;
 
+// Our custom code for Bitcoin
+mod db;
+mod txindex;
+
 pub(crate) fn hash_bytes(hash: bitcoin_serai::bitcoin::hashes::sha256d::Hash) -> [u8; 32] {
   use bitcoin_serai::bitcoin::hashes::Hash;