Add information to "Confirm fee bump" window

Check if "Coin Control features" are enabled to display warning before broadcasting replacement transaction
Workaround to fix issue: bitcoin/bitcoin#20795

Co-authored-by: Jon Atack <jon@atack.com>

src/qt/walletmodel.cpp

@@ -514,6 +514,13 @@ bool WalletModel::bumpFee(uint256 hash, uint256& new_hash)
     questionString.append("</td><td>");
     questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), new_fee));
     questionString.append("</td></tr></table>");
+
+    // Display warning in the "Confirm fee bump" window if the "Coin Control Features" option is enabled
+    if (getOptionsModel()->getCoinControlFeatures()) {
+        questionString.append("<br><br>");
+        questionString.append(tr("Warning: This may pay the additional fee by reducing change outputs or adding inputs, when necessary. It may add a new change output if one does not already exist. These changes may potentially leak privacy."));
+    }
+
     SendConfirmationDialog confirmationDialog(tr("Confirm fee bump"), questionString);
     confirmationDialog.exec();
     QMessageBox::StandardButton retval = static_cast<QMessageBox::StandardButton>(confirmationDialog.result());