pmonitor: allow FVKs to be included that do not have genesis allocs

Previously if an FVK was in the monitoring list that did not have
a genesis allocation, we'd bail out. Instead, let's just note that
its genesis balance is 0, and continue on.

crates/bin/pmonitor/src/main.rs

@@ -322,7 +322,7 @@ impl Opt {
                         *(genesis_filtered_block
                             .balances
                             .get(&fvk.to_string())
-                            .expect("wallet must have genesis allocation")),
+                            .unwrap_or(&Amount::from(0u64))),
                     ));
                 }