Multiple bug fixes / specification changes

【Details of fixes】
【Common to Welcart version and WooCommerce version】
■Fixed a bug where images with a width of 4 were stretched and displayed in the 8-block content of the top page.
■Fixed the problem that the image set for the page header image of the blog category is not reflected.
■Changed the specification of the page header overlay for products.
 Overlays (colors overlaid on images) applied to header images are now set on the category edit page.
■Corrections to OGP output content.
■Corrections to the wording of annotations, etc.

【Welcart version】
■Fixed a bug that prevented the use of “Product Category Compound Search” in the “Welcart Keyword Search” widget.

The following files have been modified for this update.
【Common to Welcart version and WooCommerce version】
【Modified file】
admin/inc/acceleration.php
admin/inc/product.php
functions/ogp.php
languages/ja.mo
languages/ja.po
style.css
template-parts/contents-builder.php
template-parts/page-header.php

【Welcart version】
【Modified file】
wc_templates/wc_search_page.php