netcmd: domain: turn domain.py into a module

The domain.py file has become quite large at over 5000 lines, splitting it now before adding more sub commands.

Signed-off-by: Rob van der Linde <rob@catalyst.net.nz>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

diff --git a/python/samba/netcmd/domain.py b/python/samba/netcmd/domain/__init__.py
similarity index 100%
rename from python/samba/netcmd/domain.py
rename to python/samba/netcmd/domain/__init__.py