Add a full-stack mint and burn test for Bitcoin and Monero

Fixes where ram_scanned is updated in processor. The prior version, while safe,
would redo massive amounts of work during periods of inactivity. It also hit an
undocumented invariant where get_eventuality_completions assumes new blocks,
yet redone work wouldn't have new blocks.

Modifies Monero's generate_blocks to return the hashes of the generated blocks.

substrate/client/src/serai/validator_sets.rs

@@ -59,6 +59,7 @@ impl Serai {
       .await
   }
 
+  // TODO: Store these separately since we almost never need both at once?
   pub async fn get_keys(&self, set: ValidatorSet) -> Result<Option<KeyPair>, SeraiError> {
     self
       .storage(PALLET, "Keys", Some(vec![scale_value(set)]), self.get_latest_block_hash().await?)