Feature/remove dependency mui system (#331)

* Remove duplicated dependency "@mui/system"

Already included in "@mui/material"

* Remove duplicated dependency "@mui/system" - Fix theme "custom" palette

Already included in "@mui/material"

* Remove duplicated dependency "@mui/system" - Fix imports

Already included in "@mui/material"

src/components/reader/pager/PagedPager.tsx

@@ -7,7 +7,7 @@
  */
 
 import React, { useEffect, useRef } from 'react';
-import { Box } from '@mui/system';
+import { Box } from '@mui/material';
 import Page from 'components/reader/Page';
 import { IReaderProps } from 'typings';