Convert the FeaturedAddress tuple to a struct

Not only did we already have multiple booleans in it, yet it theoretically
could expand in the future. Not only is this more explicit, it actually cleans
some existing code.

processor/src/coin/monero.rs

@@ -106,7 +106,10 @@ impl Monero {
     spend: dfg::EdwardsPoint,
     subaddress: Option<SubaddressIndex>,
   ) -> MoneroAddress {
-    self.view_pair(spend).address(Network::Mainnet, AddressSpec::Featured(subaddress, None, true))
+    self.view_pair(spend).address(
+      Network::Mainnet,
+      AddressSpec::Featured { subaddress, payment_id: None, guaranteed: true },
+    )
   }
 
   fn scanner(&self, spend: dfg::EdwardsPoint) -> Scanner {