Handle signing batches in the processor

Duplicates the existing signer for one tailored to batch signing.

processor/src/coins/monero.rs

@@ -1,4 +1,8 @@
-use std::{time::Duration, collections::HashMap, io};
+use std::{
+  time::{SystemTime, Duration},
+  collections::HashMap,
+  io,
+};
 
 use async_trait::async_trait;
 
@@ -142,6 +146,10 @@ impl BlockTrait<Monero> for Block {
     self.0
   }
 
+  fn time(&self) -> SystemTime {
+    SystemTime::UNIX_EPOCH + Duration::from_secs(self.1.header.timestamp)
+  }
+
   fn median_fee(&self) -> Fee {
     // TODO
     Fee { per_weight: 80000, mask: 10000 }