join: Add more framework for renaming a domain

join: Add more framework for renaming a domain

Add a DCCloneContext subclass which will rename the DB objects as they
get cloned. This uses the drs_ReplicateRenamer class added to drs_utils
in an earlier patch. Where the drs_Replicate object currently gets
created has been split out into a simple new function, which we can then
override in the rename case.

The other important difference is overriding the provision step, so that
we use the new domain-DN/realm when setting up the initial SAM DB (and
smb.conf, secrets.ldb, etc).

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>