http3: initial support for OpenSSL 3.2 QUIC stack

- HTTP/3 for curl using OpenSSL's own QUIC stack together
with nghttp3
- configure with `--with-openssl-quic` to enable curl to

http3: initial support for OpenSSL 3.2 QUIC stack

- HTTP/3 for curl using OpenSSL's own QUIC stack together
with nghttp3
- configure with `--with-openssl-quic` to enable curl to
build this. This requires the nghttp3 library
- implementation with the following restrictions:
* macOS has to use an unconnected UDP socket due to an
issue in OpenSSL's datagram implementation
See https://github.com/openssl/openssl/issues/23251
This makes connections to non-reponsive servers hang.
* GET requests will send the indicator that they have
no body in a separate QUIC packet. This may result
in processing delays or Transfer-Encodings on proxied
requests
* uploads that encounter blocks will use 100% cpu as
detection of these flow control issue is not working
(we have not figured out to pry that from OpenSSL).

Closes #12734

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