Add corners in shimmer effect for all modes

Signed-off-by: Abdourahamane BOINAIDI <abdourahamane.boinaidi@infomaniak.com>

src/main/res/layout/grid_image.xml

@@ -44,8 +44,9 @@
                 android:contentDescription="@null"
                 android:scaleType="centerCrop"
                 android:visibility="gone"
-                app:width_weight="0.4"
-                app:height_weight="0.6" />
+                app:corners="16"
+                app:height_weight="0.6"
+                app:width_weight="0.4" />
 
             <com.owncloud.android.ui.SquareImageView
                 android:id="@+id/thumbnail"

src/main/res/layout/grid_item.xml

@@ -16,6 +16,7 @@
 
 -->
 <com.owncloud.android.ui.SquareLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/ListItemLayout"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
@@ -39,7 +40,8 @@
                 android:id="@+id/thumbnail_shimmer"
                 android:layout_width="@dimen/standard_list_item_size"
                 android:layout_height="@dimen/standard_list_item_size"
-                android:visibility="gone" />
+                android:visibility="gone"
+                app:corners="8" />
 
             <ImageView
                 android:id="@+id/thumbnail"