refactor(icons): install and use @heroicons/react (#1438)

src/components/PlexLoginButton/index.tsx

@@ -1,3 +1,4 @@
+import { LoginIcon } from '@heroicons/react/outline';
 import React, { useState } from 'react';
 import { defineMessages, useIntl } from 'react-intl';
 import globalMessages from '../../i18n/globalMessages';
@@ -48,6 +49,7 @@ const PlexLoginButton: React.FC<PlexLoginButtonProps> = ({
         disabled={loading || isProcessing}
         className="plex-button"
       >
+        <LoginIcon className="w-5 h-5 mr-1" />
         {loading
           ? intl.formatMessage(globalMessages.loading)
           : isProcessing