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/wallet/scriptpubkeyman.cpp

@@ -115,6 +115,7 @@ IsMineResult IsMineInner(const LegacyDataSPKM& keystore, const CScript& scriptPu
     case TxoutType::NULL_DATA:
     case TxoutType::WITNESS_UNKNOWN:
     case TxoutType::WITNESS_V1_TAPROOT:
+    case TxoutType::ANCHOR:
         break;
     case TxoutType::PUBKEY:
         keyID = CPubKey(vSolutions[0]).GetID();