Adapt the Find/Replace dialog UI for MAC (#538)

Author: ErickWei

src/NotepadNext/dialogs/FindReplaceDialog.ui

@@ -355,6 +355,18 @@
        </property>
        <item>
         <layout class="QFormLayout" name="formLayout">
+         <property name="sizeConstraint">
+          <enum>QLayout::SetNoConstraint</enum>
+         </property>
+         <property name="fieldGrowthPolicy">
+          <enum>QFormLayout::AllNonFixedFieldsGrow</enum>
+         </property>
+         <property name="labelAlignment">
+          <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignVCenter</set>
+         </property>
+         <property name="formAlignment">
+          <set>Qt::AlignJustify|Qt::AlignTop</set>
+         </property>
          <property name="horizontalSpacing">
           <number>8</number>
          </property>