Refactor to add header to the Tracked Item pages.

lib/pages/home.dart

@@ -56,7 +56,7 @@ class _HomePageState extends State<HomePage> {
     switch (pageSelected) {
       case 0:
         page = TrackedItemPage(
-          assetsToLoad: DatabaseHelper.instance.getExpenses(),
+          assetType: ItemType.expense,
           notifyParent: refresh,
         );
         dialog = TrackedItemInputDialog(
@@ -66,7 +66,7 @@ class _HomePageState extends State<HomePage> {
         break;
       case 1:
         page = TrackedItemPage(
-          assetsToLoad: DatabaseHelper.instance.getIncomes(),
+          assetType: ItemType.income,
           notifyParent: refresh,
         );
         dialog = TrackedItemInputDialog(
@@ -76,7 +76,7 @@ class _HomePageState extends State<HomePage> {
         break;
       case 2:
         page = TrackedItemPage(
-          assetsToLoad: DatabaseHelper.instance.getAssets(),
+          assetType: ItemType.asset,
           notifyParent: refresh,
         );
         dialog = TrackedItemInputDialog(
@@ -120,15 +120,15 @@ class _HomePageState extends State<HomePage> {
       destinations: [
         NavigationRailDestination(
           icon: Icon(Icons.payment),
-          label: Text('Expenses'),
+          label: Text(ItemType.expense.plural),
         ),
         NavigationRailDestination(
           icon: Icon(Icons.account_balance),
-          label: Text('Income'),
+          label: Text(ItemType.income.plural),
         ),
         NavigationRailDestination(
           icon: Icon(Icons.attach_money),
-          label: Text('Liquid Assets'),
+          label: Text(ItemType.asset.plural),
         ),
         NavigationRailDestination(
           icon: Icon(Icons.bar_chart),