policy: Add OP_1 <0x4e73> as a standard output type

These outputs are called anchors, and allow
key-less anchor spends which are vsize-minimized
versus keyed anchors which require larger outputs
when creating and inputs when spending.

src/test/fuzz/util.cpp

@@ -213,6 +213,9 @@ CTxDestination ConsumeTxDestination(FuzzedDataProvider& fuzzed_data_provider) no
         [&] {
             tx_destination = WitnessV1Taproot{XOnlyPubKey{ConsumeUInt256(fuzzed_data_provider)}};
         },
+        [&] {
+            tx_destination = PayToAnchor{};
+        },
         [&] {
             std::vector<unsigned char> program{ConsumeRandomLengthByteVector(fuzzed_data_provider, /*max_length=*/40)};
             if (program.size() < 2) {