LibWeb: Add selector support to the new CSSParser

This is stolen from the old parser, but it seems to parse fine :^)

Userland/Libraries/LibWeb/CSS/Selector.h

@@ -53,6 +53,7 @@ public:
             HasAttribute,
             ExactValueMatch,
             Contains,
+            StartsWith,
         };
 
         AttributeMatchType attribute_match_type { AttributeMatchType::None };
@@ -67,6 +68,7 @@ public:
             Descendant,
             AdjacentSibling,
             GeneralSibling,
+            Column,
         };
         Relation relation { Relation::None };