ffi: remove quiche_rangebuf from quiche.h as it is not used anymore
ffi: remove quiche_rangebuf from quiche.h as it is not used anymore

Motivation:

quiche_rangebuf is not used anymore, we should remove it from the header file.

Modifications:

Remove unused typedef

Result:

Code cleanup
cloudflare/quiche,cloudflare/quiche,cloudflare/quiche