ThemePicker: First iteration of Grid section

Create the Fragment and provider to interface with
Launcher.
Some polish is still pending, as well as applying the grid
to the launcher.

Bug: 120560197
Change-Id: I5fc35c901a33f2163d2864bfc9e177c74d49aa36
diff --git a/res/menu/bottom_navigation_menu.xml b/res/menu/bottom_navigation_menu.xml
index a856222..d477aaf 100644
--- a/res/menu/bottom_navigation_menu.xml
+++ b/res/menu/bottom_navigation_menu.xml
@@ -23,11 +23,11 @@
     <item
         android:id="@+id/nav_clock"
         android:title="@string/clock_title"
-        android:icon="@drawable/ic_nav_grid" />
+        android:icon="@drawable/ic_nav_clock" />
     <item
         android:id="@+id/nav_grid"
         android:title="@string/grid_title"
-        android:icon="@drawable/ic_nav_theme" />
+        android:icon="@drawable/ic_nav_grid" />
     <item
         android:id="@+id/nav_wallpaper"
         android:title="@string/wallpaper_title"