Add snooze ImageView and symbol to core

Part 1 of snooze button guts setup with no visual effects
- core layout - add snooze_button ImageView
- core symbol - add `snooze_button` to core symbols
    for sysui reference via com.android.internal.R.id

Bug: 171817112
Test: manual, no regressions
Change-Id: Ie57d9f156750cecc6c48f8f905cab715142bd27d

core/res/res/layout/notification_material_action_list.xml

@@ -43,6 +43,14 @@
                 <!-- actions will be added here -->
             </com.android.internal.widget.NotificationActionListLayout>
 
+            <ImageView
+                android:id="@+id/snooze_button"
+                android:layout_width="48dp"
+                android:layout_height="48dp"
+                android:layout_gravity="center_vertical|end"
+                android:visibility="gone"
+                android:scaleType="centerInside"
+                />
             <ImageView
                 android:id="@+id/bubble_button"
                 android:layout_width="48dp"

core/res/res/values/symbols.xml

@@ -3553,6 +3553,7 @@
   <java-symbol type="id" name="clip_to_padding_tag" />
   <java-symbol type="id" name="clip_children_tag" />
   <java-symbol type="id" name="bubble_button" />
+  <java-symbol type="id" name="snooze_button" />
   <java-symbol type="dimen" name="bubble_visible_padding_end" />
   <java-symbol type="dimen" name="bubble_gone_padding_end" />
   <java-symbol type="dimen" name="text_size_body_2_material" />