lib/smbconf: add create_set_share method to SMBConf

lib/smbconf: add create_set_share method to SMBConf

Add the create_set_share method wrapping smbconf_create_set_share.
This method is one of the most complex as it must "unpack" the list
of key-value pairs from python and convert that to a `struct
smbconf_service` for the smbconfig C API.

Signed-off-by: John Mulligan <jmulligan@redhat.com>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>