enhancement(ui): improve icon design and fix code quality issues

client/app/bundles/course/material/folders/pages/BaseRetrievePage.tsx

@@ -10,9 +10,7 @@ interface BaseRetrievePageProps {
   children?: ReactNode;
 }
 
-const BaseRetrievePage = (
-  props: BaseRetrievePageProps,
-): JSX.Element => (
+const BaseRetrievePage = (props: BaseRetrievePageProps): JSX.Element => (
   <Page className="h-full m-auto flex flex-col items-center justify-center text-center">
     {props.illustration}
 

client/app/bundles/course/material/folders/pages/ErrorRetrievingFolderPage.tsx

@@ -1,7 +1,7 @@
 import React from 'react';
 import { defineMessages } from 'react-intl';
 import { useParams } from 'react-router-dom';
-import { Cancel, InsertDriveFileOutlined } from '@mui/icons-material';
+import { Cancel, FolderOutlined } from '@mui/icons-material';
 
 import Link from 'lib/components/core/Link';
 import useTranslation from 'lib/hooks/useTranslation';
@@ -35,7 +35,7 @@ const ErrorRetrievingFolderPage = (): JSX.Element => {
       description={t(translations.problemRetrievingFolderDescription)}
       illustration={
         <div className="relative">
-          <InsertDriveFileOutlined className="text-[6rem]" color="disabled" />
+          <FolderOutlined className="text-[6rem]" color="disabled" />
 
           <Cancel
             className="absolute bottom-0 -right-2 text-[4rem] bg-white rounded-full"

client/app/bundles/course/material/folders/pages/FolderShow/index.tsx

@@ -1,6 +1,6 @@
 import { FC, ReactElement, useEffect, useState } from 'react';
 import { defineMessages } from 'react-intl';
-import {useLoaderData, useParams} from 'react-router-dom';
+import { useLoaderData, useParams } from 'react-router-dom';
 
 import EditButton from 'lib/components/core/buttons/EditButton';
 import Page from 'lib/components/core/layouts/Page';