Flip iter operations to keep associated address/header/packets together
Before this change, if cast_socket_addr() returned a None for any
address/header pair, the subsequent zip() would misalign the
address/header pair and packet. So, this change zips all three together,
then does filter_map() so keep things aligned.
Additionally, compute total_size inline to avoid running through packets
a second time.
(cherry picked from commit 20b61e28b6)
Co-authored-by: steviez <steven@solana.com>
464d533da3