[wallet] Move maxTxFee to wallet

This commit moves the maxtxfee setting to the wallet. There is only
one minor behavior change:

- an error message in feebumper now refers to -maxtxfee instead of
maxTxFee.

src/interfaces/chain.cpp

@@ -339,7 +339,6 @@ public:
     CFeeRate relayMinFee() override { return ::minRelayTxFee; }
     CFeeRate relayIncrementalFee() override { return ::incrementalRelayFee; }
     CFeeRate relayDustFee() override { return ::dustRelayFee; }
-    CAmount maxTxFee() override { return ::maxTxFee; }
     bool getPruneMode() override { return ::fPruneMode; }
     bool p2pEnabled() override { return g_connman != nullptr; }
     bool isReadyToBroadcast() override { return !::fImporting && !::fReindex && !IsInitialBlockDownload(); }

src/interfaces/chain.h

@@ -216,12 +216,6 @@ public:
     //! Relay dust fee setting (-dustrelayfee), reflecting lowest rate it's economical to spend.
     virtual CFeeRate relayDustFee() = 0;
 
-    //! Node max tx fee setting (-maxtxfee).
-    //! This could be replaced by a per-wallet max fee, as proposed at
-    //! https://github.com/bitcoin/bitcoin/issues/15355
-    //! But for the time being, wallets call this to access the node setting.
-    virtual CAmount maxTxFee() = 0;
-
     //! Check if pruning is enabled.
     virtual bool getPruneMode() = 0;
 

src/interfaces/node.cpp

@@ -207,7 +207,6 @@ public:
         }
     }
     bool getNetworkActive() override { return g_connman && g_connman->GetNetworkActive(); }
-    CAmount getMaxTxFee() override { return ::maxTxFee; }
     CFeeRate estimateSmartFee(int num_blocks, bool conservative, int* returned_target = nullptr) override
     {
         FeeCalculation fee_calc;

src/interfaces/node.h

@@ -159,9 +159,6 @@ public:
     //! Get network active.
     virtual bool getNetworkActive() = 0;
 
-    //! Get max tx fee.
-    virtual CAmount getMaxTxFee() = 0;
-
     //! Estimate smart fee.
     virtual CFeeRate estimateSmartFee(int num_blocks, bool conservative, int* returned_target = nullptr) = 0;
 

src/interfaces/wallet.cpp

@@ -464,6 +464,7 @@ public:
     bool IsWalletFlagSet(uint64_t flag) override { return m_wallet->IsWalletFlagSet(flag); }
     OutputType getDefaultAddressType() override { return m_wallet->m_default_address_type; }
     OutputType getDefaultChangeType() override { return m_wallet->m_default_change_type; }
+    CAmount getDefaultMaxTxFee() override { return m_wallet->m_default_max_tx_fee; }
     void remove() override
     {
         RemoveWallet(m_wallet);

src/interfaces/wallet.h

@@ -247,6 +247,9 @@ public:
     // Get default change type.
     virtual OutputType getDefaultChangeType() = 0;
 
+    //! Get max tx fee.
+    virtual CAmount getDefaultMaxTxFee() = 0;
+
     // Remove wallet.
     virtual void remove() = 0;