Fixed multiple bugs

【Contents of the fix】
■Fixed a bug in the search results page that articles with “Fix this post at the top” checked were displayed at the top regardless of the search condition.
■Fixed a bug that search results are not displayed when searching for tags on pages other than the first page of search results.
■Fixed a bug in WordPress 5.5 that selecting a category to display in the category list in the content builder does not save the category.

【Fixed files】
admin/contents_builder.php
custom_search_results.php
functions.php
style.css