feat(main): Introduce USP block type and custom classes for HTML groups

This release adds a new "USP" (Unique Selling Proposition) block type,
allowing for flexible display of image-based selling points with optional links.

Additionally, administrators can now assign custom CSS classes to Custom HTML Groups,
enhancing layout and styling capabilities.

Includes a refinement to the FAQ accordion template to ensure questions without answers
do not display a collapse button, improving usability.

Updates module version to 1.13.0 with a database upgrade script for the new `custom_class` column.

views/css/front/customhtml.css

@@ -48,6 +48,21 @@
     margin-right: 0.5rem;
 }
 
+.customhtml-usp {
+    gap: 0.5rem;
+    color: inherit;
+    text-decoration: none;
+}
+
+.customhtml-usp-icon img {
+    max-height: 32px;
+    width: auto;
+}
+
+.customhtml-usp-text {
+    font-weight: 500;
+}
+
 /* FAQ */
 .accordion-icon-minus {
     display: block;