add a corner on the background of the shimmer

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

src/main/res/drawable/shimmer_background.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
+    <solid android:color="@color/grey_200"/>
+    <corners android:radius="@dimen/file_icon_rounded_corner_radius"/>
+</shape>

src/main/res/layout/grid_image.xml

@@ -42,7 +42,7 @@
                 android:id="@+id/thumbnail_shimmer"
                 android:layout_width="match_parent"
                 android:layout_height="@dimen/standard_list_item_size"
-                android:background="@color/grey_200"
+                android:background="@drawable/shimmer_background"
                 android:padding="@dimen/standard_eigth_padding"
                 android:visibility="gone" />
 

src/main/res/layout/grid_item.xml

@@ -42,7 +42,7 @@
                 android:id="@+id/thumbnail_shimmer"
                 android:layout_width="@dimen/standard_list_item_size"
                 android:layout_height="@dimen/standard_list_item_size"
-                android:background="@color/grey_200"
+                android:background="@drawable/shimmer_background"
                 android:visibility="gone" />
 
             <ImageView

src/main/res/layout/list_item.xml

@@ -48,7 +48,8 @@
                 android:id="@+id/thumbnail_shimmer"
                 android:layout_width="@dimen/file_icon_size"
                 android:layout_height="@dimen/file_icon_size"
-                android:background="@color/grey_200"
+                android:layout_marginStart="@dimen/standard_half_margin"
+                android:background="@drawable/shimmer_background"
                 android:visibility="gone" />
 
             <ImageView