HPCC-11764 Dafilesrv authentication and encryption on transport

Current dafilesrv uses unencrypted sockets which is not secure. This update
adds a new section to the environment.conf file to optionally specify that
dafilesrv and its clients should use SSL, and points to the cert file, key file
and provides an encrypted passphrase. If specified, dafilesrv and its clients
will enable secure sockets (openSSL) and communicate in a secure manner.

Signed-off-by: William Whitehead <william.whitehead@lexisnexis.com>
I think ok using a new specific select for multi, the alternative was to use a createSocketEpollHandler and add each socket and use ISocketSelectNotify's to get notification..

As there only 2, it's probably ok and/or better (as lower overhead)

@mckellyln - any thoughts on new wait_read_multiple method use here?