Push catch_preprocessor include down from test_macros header

src/catch2/generators/catch_generators.hpp

@@ -12,6 +12,8 @@
 #include <catch2/internal/catch_source_line_info.hpp>
 #include <catch2/internal/catch_stringref.hpp>
 #include <catch2/internal/catch_move_and_forward.hpp>
+#include <catch2/internal/catch_unique_name.hpp>
+#include <catch2/internal/catch_preprocessor.hpp>
 
 #include <vector>
 #include <tuple>