Implement enable sidestaking user checkbox in GUI options.

src/qt/forms/optionsdialog.ui

@@ -320,6 +320,13 @@
           </item>
          </layout>
         </item>
+        <item>
+         <widget class="QCheckBox" name="enableSideStaking">
+          <property name="text">
+           <string>Enable Locally Specified Sidestaking</string>
+          </property>
+         </widget>
+        </item>
        </layout>
       </widget>
      </widget>

src/qt/optionsdialog.cpp

@@ -176,6 +176,7 @@ void OptionsDialog::setMapper()
     mapper->addMapping(ui->enableStakeSplit, OptionsModel::EnableStakeSplit);
     mapper->addMapping(ui->stakingEfficiency, OptionsModel::StakingEfficiency);
     mapper->addMapping(ui->minPostSplitOutputValue, OptionsModel::MinStakeSplitValue);
+    mapper->addMapping(ui->enableSideStaking, OptionsModel::EnableSideStaking);
 
     /* Window */
     mapper->addMapping(ui->disableTransactionNotifications, OptionsModel::DisableTrxNotifications);

src/qt/optionsmodel.cpp

@@ -152,6 +152,9 @@ QVariant OptionsModel::data(const QModelIndex & index, int role) const
         case EnableStakeSplit:
             // This comes from the core and is a read-write setting (see below).
             return QVariant(gArgs.GetBoolArg("-enablestakesplit"));
+        case EnableSideStaking:
+            // This comes from the core and is a read-write setting (see below).
+            return QVariant(gArgs.GetBoolArg("-enablesidestaking"));
         case StakingEfficiency:
             // This comes from the core and is a read-write setting (see below).
             return QVariant((double) gArgs.GetArg("-stakingefficiency", (int64_t) 90));
@@ -303,10 +306,15 @@ bool OptionsModel::setData(const QModelIndex & index, const QVariant & value, in
         case EnableStakeSplit:
             // This is a core setting stored in the read-write settings file and once set will override the read-only
             //config file.
-            //fStakeSplitEnabled = value.toBool();
             gArgs.ForceSetArg("-enablestakesplit", value.toBool() ? "1" : "0");
             updateRwSetting("enablestakesplit", gArgs.GetBoolArg("-enablestakesplit"));
             break;
+        case EnableSideStaking:
+            // This is a core setting stored in the read-write settings file and once set will override the read-only
+            //config file.
+            gArgs.ForceSetArg("-enablesidestaking", value.toBool() ? "1" : "0");
+            updateRwSetting("enablesidestaking", gArgs.GetBoolArg("-enablesidestaking"));
+            break;
         case StakingEfficiency:
             // This is a core setting stored in the read-write settings file and once set will override the read-only
             //config file.

src/qt/optionsmodel.h

@@ -41,6 +41,7 @@ class OptionsModel : public QAbstractListModel
         DataDir,                 // QString
         EnableStaking,           // bool
         EnableStakeSplit,        // bool
+        EnableSideStaking,       // bool
         StakingEfficiency,       // double
         MinStakeSplitValue,      // int
         ContractChangeToInput,   // bool