LibHTML: Start building a simple code generator for CSS properties

Code for parsing and stringifying CSS properties is now generated based
on LibHTML/CSS/Properties.json

At the moment, the file tells us three things:

- The name of a property
- Its initial value
- Whether it's inherited

Also, for shorthand properties, it provides a list of all the longhand
properties it may expand too. This is not actually used in the engine
yet though.

This *finally* makes layout tree dumps show the names of CSS properties
in effect, instead of "CSS::PropertyID(32)" and such. :^)

Libraries/LibHTML/Dump.cpp

@@ -1,4 +1,5 @@
 #include <AK/Utf8View.h>
+#include <LibHTML/CSS/PropertyID.h>
 #include <LibHTML/CSS/StyleSheet.h>
 #include <LibHTML/DOM/Comment.h>
 #include <LibHTML/DOM/Document.h>
@@ -128,7 +129,7 @@ void dump_tree(const LayoutNode& layout_node)
     layout_node.style().for_each_property([&](auto property_id, auto& value) {
         for (int i = 0; i < indent; ++i)
             dbgprintf("    ");
-        dbgprintf("  (CSS::PropertyID(%u): %s)\n", (unsigned)property_id, value.to_string().characters());
+        dbgprintf("  (%s: %s)\n", CSS::string_from_property_id(property_id), value.to_string().characters());
     });
 
     ++indent;