Expose "new" ap_parse_form_data() function instead of requiring mod_request for any module that may want to parse form data...

You don't export the fn hooked or registered as an optional fn

No. You cannot rely on mod_foo.h magic from the various subdirectories if you will consume it in the core (server/*.c). server/request.c needs mod_request (similar to mod_core.h) so this never belonged in the subdir.

Move the KeptBodySize directive, kept_body filters and the ap_parse_request_body function out of the http module and into a new module called mod_request, reducing the size of the core.