net: posix: add posix_connected_socket_operations for unix domain sockets
net: posix: add posix_connected_socket_operations for unix domain sockets

Increase the similarity between unix-domain and inet sockets, before we
unify them.

scylladb/seastar,cloudius-systems/seastar,cloudius-systems/seastar,avikivity/seastar,syuu1228/seastar,cloudius-systems/seastar,dreamsxin/seastar,syuu1228/seastar,scylladb/seastar,scylladb/seastar,dreamsxin/seastar,syuu1228/seastar,avikivity/seastar,dreamsxin/seastar,avikivity/seastar