Fully initialize ngtcp2_transport_params
Fully initialize ngtcp2_transport_params

Node.js makes the full `ngtcp2_transport_params` struct available
for storage as a byte array, including any possible padding
in the struct.

Fully initializing the struct with `memset()` makes this deterministic.

ngtcp2/ngtcp2,ngtcp2/ngtcp2,ngtcp2/ngtcp2