Remove assorted internal functionalities

[waynew]

• salt.utils.context.NamespacedDictWrapper
• salt.utils.minions show_ipv4 parameter removed
• salt.utils.smb.get_conn - no longer supports impacket, use smbprotocol instead
• salt.utils.cloud dropped winexe support - use pypsexec instead
• salt.transport.zeromq.AsyncZeroMQReqChannel, .AsyncReqMessageClientPool, and .AsyncReqMessageClient .destroy methods removed. Use .close instead
• salt.transport.Channel removed - use salt.transport.client.ReqChannel instead