ERL-1138: Create gen_udp, gen_tcp, and gen_sctp from bound file descriptor

[OTP-Maintainer]

Original reporter: hauleth Affected version: Not Specified Component: kernel Migrated from: https://bugs.erlang.org/browse/ERL-1138

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It would be very nice to have possibility to create {{gen_*}} connections from already bound file descriptor. Currently passing {{{fd, Fd}}} will always try to bind connection which prevents using {{systemd}} (and possibly other tools) for socket activation.