add textview for typing indicator

Signed-off-by: Marcel Hibbe <dev@mhibbe.de>

app/src/main/res/layout/activity_chat.xml

@@ -161,6 +161,15 @@
             android:layout_height="1dp"
             android:background="@color/controller_chat_separator" />
 
+        <TextView
+            android:id="@+id/typing_indicator"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="@dimen/side_margin"
+            android:layout_marginEnd="@dimen/side_margin"
+            tools:text="Marcel is typing">
+        </TextView>
+
         <com.nextcloud.talk.ui.MessageInput
             android:id="@+id/messageInputView"
             android:layout_width="match_parent"