r25940: Rework the samldb and templates handling.

r25940: Rework the samldb and templates handling.

Templates just don't belong in the sam.ldb, as they don't obey any of
the other rules.  This moves them to a seperate templates.ldb.

In samldb, this patch reworks the duplicate SID and Name detection
code, to use ldb_search_exp_fmt() rather than gendb_search.  This
returns far more useful errors, which we now handle and report better.

The call to samdb_search_for_parent_domain() has been moved in samldb,
to allow both the account and SID uniqueness checks to be in the same
domain.  This function also returns better errors.

dcesrv_drsuapi.c is updated for the new prototype of
samdb_search_for_parent_domain()

Andrew Bartlett
(This used to be commit f1ab90c88c782c693b41795d70368650806543b5)