OpenSSL 3.2.0, QUIC, macOS, error 56 on connected UDP socket

OpenSSL 3.2.0, QUIC, macOS, error 56 on connected UDP socket

current `translate_msg()` function attempts to set `->msg_name`
(and `->msg_namelen`) with `BIO`'s peer name (connection destination)
regardless if underlying socket is connected or not. Such implementation
uncovers differences in socket implementation between various OSes.

As we have learned hard way `sendmsg()` and `sendmmsg()` on `OpenBSD`
and (`MacOS` too) fail to send messages with `->msg_name` being
set on connected socket. In such case the caller receives
`EISCON` errro.

I think `translate_msg()` caller should provide a hint to indicate
whether we deal with connected (or un-connected) socket. For
connected sockets the peer's name should not be set/filled
by `translate_msg()`. On the other hand if socket is un-connected,
then `translate_msg()` must populate `->msg_name` and `->msg_namelen`
members.

The caller can use `getpeername(2)` to see if socket is
connected. If `getpeername()` succeeds then we must be dealing
with connected socket and `translate_msg()` must not set
`->msg_name` and `->msg_namelen` members. If `getpeername(2)`
fails, then `translate_msg()` must provide peer's name (destination
address) in `->msg_name` and set `->msg_namelen` accordingly.

The propposed fix introduces `is_connected()` function,
which applies `getpeername()` to socket bound to `BIO` instance.
The `dgram_sendmmsg()` uses `is_connected()` as a hint
for `translate_msg()` function, so msghdr gets initialized
with respect to socket state.

The change also modifies existing `test/quic_client_test.c`
so it also covers the case of connected socket. To keep
things simple we can introduce optional argument `connect_first`
to `./quic_client_test` function. Without `connect_first`
the test run as usual. With `connect_first` the test creates
and connects socket first. Then it passes such socket to
`BIO` sub-system to perform `QUIC` connect test as usual.

Fixes #23251

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23396)