ngtcp2: Support the latest update key callback type

[jay]

• Remove our cb_update_key in favor of ngtcp2's new
  ngtcp2_crypto_update_key_cb which does the same thing.

Several days ago the ngtcp2_update_key callback function prototype was
changed in ngtcp2/ngtcp2@42ce09c. Though it would be possible to
fix up our cb_update_key for that change they also added
ngtcp2_crypto_update_key_cb which does the same thing so we'll use that
instead.

Ref: ngtcp2/ngtcp2@42ce09c

Closes #xxxx

---

Disclaimer: I'm not yet using HTTP/3. This is an attempt to fix this CI error:

  CC       vquic/libcurl_la-ngtcp2.lo
vquic/ngtcp2.c:559:3: error: initialization of ‘int (*)(ngtcp2_conn *, uint8_t *, uint8_t *, uint8_t *, uint8_t *, uint8_t *, uint8_t *, const uint8_t *, const uint8_t *, size_t,  void *)’ {aka ‘int (*)(struct ngtcp2_conn *, unsigned char *, unsigned char *, unsigned char *, unsigned char *, unsigned char *, unsigned char *, const unsigned char *, const unsigned char *, long unsigned int,  void *)’} from incompatible pointer type ‘int (*)(ngtcp2_conn *, uint8_t *, uint8_t *, uint8_t *, uint8_t *, void *)’ {aka ‘int (*)(struct ngtcp2_conn *, unsigned char *, unsigned char *, unsigned char *, unsigned char *, void *)’} [-Werror=incompatible-pointer-types]
   cb_update_key, /* update_key */
   ^~~~~~~~~~~~~
vquic/ngtcp2.c:559:3: note: (near initialization for ‘ng_callbacks.update_key’)

[bagder]

👍 - this fixes the build and I tried curl --http3 successfully against https://nghttp2.org:4433/ several times.

[tatsuhiro-t]

Now that secrets are stored into ngtcp2_conn object, curl no longer needs to store them. qs->rx_secret and qs->tx_secret can be removed.

[jay]

Now that secrets are stored into ngtcp2_conn object, curl no longer needs to store them. qs->rx_secret and qs->tx_secret can be removed.

Ok thanks, I have just amended the proposed changes to remove tx/rx secret from quicsocket entirely.