[Provider Model] Internet Panel - Airplane mode is on

- Add "Airplane mode is on" to sub-title
  - Set the header layout to CENTER_HORIZONTAL if it's no icon

- Hide "Settings" button

- Screenshot
  https://screenshot.googleplex.com/6m5dFVZu7ar4nKW

Bug: 178717651
Test: manual test
atest InternetConnectivityPanelTest \
      PanelFragmentTest \
      ProviderModelSliceTest

Change-Id: I899a817fd99415e9cad608aa4deac1e45365696a

res/layout/panel_layout.xml

@@ -48,11 +48,13 @@
             </LinearLayout>
 
             <LinearLayout
+                android:id="@+id/header_layout"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:layout_marginStart="16dp"
                 android:layout_marginEnd="16dp"
                 android:orientation="vertical">
+
                 <TextView
                     android:id="@+id/header_title"
                     android:layout_width="wrap_content"
@@ -67,8 +69,7 @@
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:ellipsize="end"
-                    android:maxLines="1" />
-
+                    android:maxLines="1"/>
             </LinearLayout>
         </LinearLayout>