LibWeb/CSS: Add functions that report font format/technology support

Both `@supports` and `@font-face` need this. There may be some automatic
way of querying whether our renderer supports these, but I couldn't
figure it out, so here's a basic hard-coded list. I think the font-tech
list has false negatives, as I don't know enough about fonts to
determine what we support accurately.

Libraries/LibWeb/CSS/FontFace.h

@@ -113,4 +113,7 @@ private:
     bool m_is_css_connected { false };
 };
 
+bool font_format_is_supported(FlyString const& name);
+bool font_tech_is_supported(FlyString const& name);
+
 }