Add support for simultaneous use of UDP and TCP sockets

Add support for simultaneous use of UDP and TCP sockets

Add all the bound sockets to the event loop.
The main server loop has been updated to handle both
TCP and UDP connections.
The hash function has also been modified to include the
protocol during the creation of new client instances.
There are also a couple of refinements to make the
whole code flow management capable of handling
different kind of clients:

MULTI: properly remove TCP instances by checking the multi_instance
       protocol instead of the global one.

TLS: set the tls_option xmit_hold bool value to true only in case of
     TCP child instance to avoid checking the global protocol
     value.

INIT: initialize the c->c2.event_set in the inherit_context_top()
      by default and not only in case of UDP since we could have
      multiple different sockets.

Change-Id: I31bbf87e4e568021445c7512ecefadfd4a69b363
Signed-off-by: Gianmarco De Gregori <gianmarco@mandelbit.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20250306095928.10229-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31028.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>