Multiple bug fixes

【Contents of the fix】
■Fixed a mistake in the description of the footer SNS button.
■Updated the page builder.
・【Firefox, IE】Fixed a bug that caused unstable display of Google map.
・Fixed the bug of switching editor and adjusted CSS in WordPress 5.5.
・Fixed other minor bugs.
■【iPhone】Fixed a bug that the Hatena bookmark icon was not displayed on the share button in the fixed footer bar.

The following files have been fixed in this update.

【Modified file】
css/footer-bar.css
footer-bar.php
footer.php
functions/update_notifier.php
languages/ja.mo
languages/ja.po
pagebuilder/assets/admin/css/admin.css
pagebuilder/assets/admin/js/admin.js
pagebuilder/assets/admin/js/editor.js
pagebuilder/assets/admin/js/repeater.js
pagebuilder/assets/admin/js/simple_table.js
pagebuilder/assets/admin/js/slider.js
pagebuilder/modules/googlemap.php
pagebuilder/modules/simple_table.php
pagebuilder/modules/slider.php
pagebuilder/pagebuilder.php
style.css
widget/google_search.php

【Added files】
img/common/hatenabookmark-logomark.svg