UI fixes for system bars

- Darken alpha on unselected nav bar icons
- Add ripple effect to status icons pill and driver username pill

Bug: 169711878
Test: manual
Change-Id: Ida126155a93948ec4990556ffb675d94e3c87369

packages/CarSystemUI/res/drawable/system_bar_background_pill.xml

@@ -14,9 +14,20 @@
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
   -->
-
-<shape xmlns:android="http://schemas.android.com/apk/res/android"
-       android:shape="rectangle">
-  <solid android:color="@color/system_bar_background_pill_color"/>
-  <corners android:radius="30dp"/>
-</shape>
+<layer-list
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt">
+    <item>
+        <aapt:attr name="android:drawable">
+            <shape android:shape="rectangle">
+                <solid android:color="@color/system_bar_background_pill_color"/>
+                <corners android:radius="30dp"/>
+            </shape>
+        </aapt:attr>
+    </item>
+    <item>
+        <aapt:attr name="android:drawable">
+            <ripple android:color="?android:attr/colorControlHighlight"/>
+        </aapt:attr>
+    </item>
+</layer-list>

packages/CarSystemUI/res/values/styles.xml

@@ -49,5 +49,6 @@
         <item name="android:padding">@dimen/system_bar_button_padding</item>
         <item name="android:gravity">center</item>
         <item name="android:background">?android:attr/selectableItemBackground</item>
+        <item name="unselectedAlpha">0.56</item>
     </style>
 </resources>