adds log update function and log list

- log updates in background automatically
  from server data
- log list in main screen of app is updated
  showing the title of each notification

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

@@ -45,6 +45,7 @@
         app:layout_constraintStart_toStartOf="parent"/>
 
     <LinearLayout
+        android:id="@+id/buttons"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:orientation="horizontal"
@@ -68,4 +69,35 @@
             android:textColor="@color/white"
             android:text="@string/view_sender" />
     </LinearLayout>
+
+    <LinearLayout
+        android:id="@+id/header"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:layout_marginTop="20dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/buttons"
+        app:layout_constraintStart_toStartOf="parent">
+    <TextView
+        android:id="@+id/nr_messages"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/default_nr_messages"
+        android:layout_marginEnd="10dp"
+        android:textSize="20sp"/>
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/message_header"
+        android:textSize="20sp"/>
+    </LinearLayout>
+
+    <ListView
+        android:id="@+id/notification_list"
+        android:layout_width="match_parent"
+        android:layout_margin="20sp"
+        android:layout_height="wrap_content"
+        app:layout_constraintTop_toBottomOf="@id/header">
+    </ListView>
 </androidx.constraintlayout.widget.ConstraintLayout>