Allow more htmlClasses

Supports classes with !important as used in Tailwind 3
https://tailwindcss.com/docs/configuration#important-modifier

<p class="font-bold md:!font-medium">

Author: in-session

lib/internal/Magento/Framework/View/Layout/etc/elements.xsd

@@ -119,7 +119,7 @@
 
     <xs:simpleType name="htmlClassType">
         <xs:restriction base="xs:string">
-            <xs:pattern value="[a-zA-Z\d\-_/:.\[\]&amp;@() ]*"/>
+            <xs:pattern value="[a-zA-Z\d\-_/:.\[\]&amp;@()! ]*"/>
         </xs:restriction>
     </xs:simpleType>