[bdk_chain_redesign] Implement OwnedIndexer for indexers

`SpkTxOutIndex` and `KeychainTxOutIndex` now both implement
`OwnedIndexer`.

crates/chain/src/spk_txout_index.rs

@@ -2,7 +2,7 @@ use core::ops::RangeBounds;
 
 use crate::{
     collections::{hash_map::Entry, BTreeMap, BTreeSet, HashMap},
-    indexed_tx_graph::Indexer,
+    indexed_tx_graph::{Indexer, OwnedIndexer},
     ForEachTxOut,
 };
 use bitcoin::{self, OutPoint, Script, Transaction, TxOut, Txid};
@@ -75,6 +75,12 @@ impl<I: Clone + Ord + 'static> Indexer for SpkTxOutIndex<I> {
     }
 }
 
+impl<I: Clone + Ord + 'static> OwnedIndexer for SpkTxOutIndex<I> {
+    fn is_spk_owned(&self, spk: &Script) -> bool {
+        self.spk_indices.get(spk).is_some()
+    }
+}
+
 /// This macro is used instead of a member function of `SpkTxOutIndex`, which would result in a
 /// compiler error[E0521]: "borrowed data escapes out of closure" when we attempt to take a
 /// reference out of the `ForEachTxOut` closure during scanning.