Monero: fix decoy selection algo and add test for latest spendable (#384)

* Monero: fix decoy selection algo and add test for latest spendable

- DSA only selected coinbase outputs and didn't match the wallet2
implementation
- Added test to make sure DSA will select a decoy output from the
most recent unlocked block
- Made usage of "height" in DSA consistent with other usage of
"height" in Monero code (height == num blocks in chain)
- Rely on monerod RPC response for output's unlocked status

* xmr runner tests mine until outputs are unlocked

* fingerprintable canoncial select decoys

* Separate fingerprintable canonical function

Makes it simpler for callers who are unconcered with consistent
canonical output selection across multiple clients to rely on
the simpler Decoy::select and not worry about fingerprintable
canonical

* fix merge conflicts

* Put back TODO for issue #104

* Fix incorrect check on distribution len

The RingCT distribution on mainnet doesn't start until well after
genesis, so the distribution length is expected to be < height.

To be clear, this was my mistake from this series of changes
to the DSA. I noticed this mistake because the DSA would error
when running on mainnet.

tests/full-stack/src/tests/mint_and_burn.rs

@@ -100,7 +100,7 @@ async fn mint_and_burn_test() {
         let rpc = producer_handles.monero(ops).await;
         let mut res = Vec::with_capacity(count);
         for _ in 0 .. count {
-          let block = rpc.get_block(rpc.generate_blocks(&addr, 1).await.unwrap()[0]).await.unwrap();
+          let block = rpc.get_block(rpc.generate_blocks(&addr, 1).await.unwrap().0[0]).await.unwrap();
 
           let mut txs = Vec::with_capacity(block.txs.len());
           for tx in &block.txs {
@@ -360,11 +360,11 @@ async fn mint_and_burn_test() {
         .unwrap()
         .swap_remove(0);
 
-      let decoys = Decoys::select(
+      let decoys = Decoys::fingerprintable_canonical_select(
         &mut OsRng,
         &rpc,
         Protocol::v16.ring_len(),
-        rpc.get_height().await.unwrap() - 1,
+        rpc.get_height().await.unwrap(),
         &[output.clone()],
       )
       .await