Add field dragger to vector inputs

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Controls/VectorControl.cs

 
         void AddField(int index, string subLabel)
         {
-            Add(new Label(subLabel));
+            var label = new Label(subLabel);
+            Add(label);
+            var dragger = new FieldMouseDragger<double>(doubleField);
+            dragger.SetDragZone(label);
             doubleField.RegisterCallback<MouseDownEvent>(Repaint);
             doubleField.RegisterCallback<MouseMoveEvent>(Repaint);
             doubleField.OnValueChanged(evt =>
                 SetValue(value);
                 m_UndoGroup = -1;
+                Dirty(ChangeType.Repaint);
             });
             doubleField.RegisterCallback<InputEvent>(evt =>
             {
                 var value = GetValue();
                 value[index] = newValue;
                 SetValue(value);
+                Dirty(ChangeType.Repaint);
             });
             doubleField.RegisterCallback<KeyDownEvent>(evt =>
             {

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Views/Slots/MultiFloatSlotControlView.cs

 
         void AddField(Vector4 initialValue, int index, string subLabel)
         {
-            Add(new Label(subLabel));
+            var label = new Label(subLabel);
+            Add(label);
+            var dragger = new FieldMouseDragger<double>(doubleField);
+            dragger.SetDragZone(label);
             doubleField.OnValueChanged(evt =>
             {
                 var value = m_Get();

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Resources/Styles/MaterialGraph.uss

 MultiFloatSlotControlView > Label {
     margin-left: 0;
     margin-right: 0;
+    cursor: slide-arrow;
 }
 
 MultiFloatSlotControlView > DoubleField {
 MultiFloatControlView > Label {
     margin-left: 0;
     margin-right: 0;
+    cursor: slide-arrow;
 }
 
 MultiFloatControlView > DoubleField {