fix: spks_of_all_keychains() shouldn't return an..

..infinite iterator for non-wildcard descriptors

We would previously use `new_with_range`, which didn't check if
the descriptor had a wildcard or not. This meant that for non-wildcard
descriptors we created a spkiterator that would go on producing
the same spk over and over again; this caused some scanning issues
with electrum and esplora.

To reproduce the bug, run in `example-crates/example_electrum`:
```
cargo run "sh(wsh(or_d(c:pk_k(cPGudvRLDSgeV4hH9NUofLvYxYBSRjju3cpiXmBg9K8G9k1ikCMp),c:pk_k(cSBSBHRrzqSXFmrBhLkZMzQB9q4P9MnAq92v8d9a5UveBc9sLX32))))#zp9pcfs9" scan
```

Author: danielabrozzoni

crates/chain/src/keychain/txout_index.rs

@@ -270,12 +270,7 @@ impl<K: Clone + Ord + Debug> KeychainTxOutIndex<K> {
     ) -> BTreeMap<K, SpkIterator<Descriptor<DescriptorPublicKey>>> {
         self.keychains
             .iter()
-            .map(|(keychain, descriptor)| {
-                (
-                    keychain.clone(),
-                    SpkIterator::new_with_range(descriptor.clone(), 0..),
-                )
-            })
+            .map(|(keychain, descriptor)| (keychain.clone(), SpkIterator::new(descriptor.clone())))
             .collect()
     }
 
@@ -291,7 +286,7 @@ impl<K: Clone + Ord + Debug> KeychainTxOutIndex<K> {
             .get(keychain)
             .expect("keychain must exist")
             .clone();
-        SpkIterator::new_with_range(descriptor, 0..)
+        SpkIterator::new(descriptor)
     }
 
     /// Convenience method to get [`revealed_spks_of_keychain`] of all keychains.