Improve C++ highlighting for sized type specifiers

For consistency, sized type specifiers should be highlighted the same
way as primitive types, to make sure 'unsigned', 'int' and 'unsigned
int' are all the same color. A previous change moved primitive types
from @Keyword to @type, and this adjusts the sized type specifier to
follow suit.

crates/languages/src/cpp/highlights.scm

@@ -69,6 +69,7 @@
 (auto) @type
 (type_identifier) @type
 type :(primitive_type) @type.primitive
+(sized_type_specifier) @type.primitive
 
 (requires_clause
     constraint: (template_type
@@ -131,7 +132,6 @@ type :(primitive_type) @type.primitive
   "using"
   "virtual"
   "while"
-  (sized_type_specifier)
   (storage_class_specifier)
   (type_qualifier)
 ] @keyword