improvement(browser-appearance): use 'restore' icon

User feedback: 'restore to default' wasn't obvious

Source: https://pictogrammers.com/library/mdi/icon/restore/

AnkiDroid/src/main/res/drawable/ic_restore_variant.xml

@@ -0,0 +1,2 @@
+<!-- drawable/restore.xml -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:width="24dp" android:tint="?attr/colorControlNormal" android:viewportWidth="24" android:viewportHeight="24"><path android:fillColor="#000000" android:pathData="M13,3A9,9 0 0,0 4,12H1L4.89,15.89L4.96,16.03L9,12H6A7,7 0 0,1 13,5A7,7 0 0,1 20,12A7,7 0 0,1 13,19C11.07,19 9.32,18.21 8.06,16.94L6.64,18.36C8.27,20 10.5,21 13,21A9,9 0 0,0 22,12A9,9 0 0,0 13,3Z" /></vector>

AnkiDroid/src/main/res/menu/card_template_browser_appearance_editor.xml

@@ -19,7 +19,7 @@
     xmlns:ankidroid="http://schemas.android.com/apk/res-auto">
     <item
         android:id="@+id/action_restore_default"
-        android:icon="@drawable/ic_clear_white"
+        android:icon="@drawable/ic_restore_variant"
         android:title="@string/restore_default"
         ankidroid:showAsAction="ifRoom"
         android:visible="true"/>