chore: Loading placeholders (#2322)

* Improve visual of loading mask

* Normalize placeholder naming

* Remove unused file

app/components/PaginatedList.js

@@ -7,7 +7,7 @@ import * as React from "react";
 import { Waypoint } from "react-waypoint";
 import { DEFAULT_PAGINATION_LIMIT } from "stores/BaseStore";
 import DelayedMount from "components/DelayedMount";
-import { ListPlaceholder } from "components/LoadingPlaceholder";
+import PlaceholderList from "components/List/Placeholder";
 
 type Props = {
   fetch?: (options: ?Object) => Promise<void>,
@@ -128,7 +128,7 @@ class PaginatedList extends React.Component<Props> {
         )}
         {showLoading && (
           <DelayedMount>
-            <ListPlaceholder count={5} />
+            <PlaceholderList count={5} />
           </DelayedMount>
         )}
       </>