refactor: add OrphanTxBase for external use

Enables external entities to obtain orphan
information

src/txorphanage.cpp

@@ -33,7 +33,7 @@ bool TxOrphanage::AddTx(const CTransactionRef& tx, NodeId peer)
         return false;
     }
 
-    auto ret = m_orphans.emplace(wtxid, OrphanTx{tx, peer, Now<NodeSeconds>() + ORPHAN_TX_EXPIRE_TIME, m_orphan_list.size()});
+    auto ret = m_orphans.emplace(wtxid, OrphanTx{{tx, peer, Now<NodeSeconds>() + ORPHAN_TX_EXPIRE_TIME}, m_orphan_list.size()});
     assert(ret.second);
     m_orphan_list.push_back(ret.first);
     for (const CTxIn& txin : tx->vin) {

src/txorphanage.h

@@ -72,11 +72,15 @@ public:
         return m_orphans.size();
     }
 
-protected:
-    struct OrphanTx {
+    /** Allows providing orphan information externally */
+    struct OrphanTxBase {
         CTransactionRef tx;
         NodeId fromPeer;
         NodeSeconds nTimeExpire;
+    };
+
+protected:
+    struct OrphanTx : public OrphanTxBase {
         size_t list_pos;
     };