fix to align progress bar in center of files

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

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

@@ -33,7 +33,7 @@
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginStart="2dp"
-        android:layout_marginEnd="2dp"
+        android:layout_marginEnd="@dimen/standard_margin"
         android:adjustViewBounds="true"
         app:layout_alignSelf="flex_start"
         app:layout_flexGrow="1"
@@ -46,7 +46,6 @@
             android:layout_height="@dimen/mediatab_file_icon_size"
             android:padding="4dp"
             android:src="@drawable/ic_mimetype_file"
-            android:layout_marginEnd="@dimen/standard_margin"
             app:layout_constraintTop_toTopOf="parent"
             app:placeholderImageScaleType="fitCenter"
             fresco:actualImageScaleType="centerCrop"