Limit subject length in headers to 255 characters

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

@@ -253,6 +253,7 @@
         android:layout_marginEnd="6dp"
         android:ellipsize="end"
         android:gravity="center_vertical"
+        android:maxLength="255"
         android:minHeight="21dp"
         android:singleLine="true"
         android:text="Subject"

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

@@ -174,6 +174,7 @@
         android:layout_marginTop="6dp"
         android:layout_marginEnd="6dp"
         android:gravity="center_vertical"
+        android:maxLength="255"
         android:minHeight="24dp"
         android:text="Subject"
         android:textAppearance="@style/TextAppearance.AppCompat.Medium"