This replace the dsdb_syntax_FOOBAR_ldb_to_drsuapi function,
which was left as a TODO code. Implementation in both added functions
is completely identical and probably should differ in the future.

This one copes with deleted objects where linked attributes have been
set on the module. We hit this when we do the ldb wipe at the start of
a provision, which trigers linked attribute updates, but for objects
that have disappeared. We need to ensure that the linked attribute
updates only happen on the right object, and if the object gets
re-created (as happens with a provision) then it is not the right
object.

To cope with this we record the GUID of the object when the operation
that triggered the linked attribute update comes in, and then find the
DN by suing that GUID when we apply the change in the prepare commit
hook.

This allows for safe transaction end aborts

Now that ldb is calling prepare commit separately, the job of the
partition module on transaction end is much simpler (and more robust!)

This will be used by the linked_attribute module

When running at functional level 2 or above, the repl_meta_data module
can receive linked attribute structures from the repl replication
task. These attributes can come through DRS before the associated
objects have been created. To cope with this, we need to process
linked attributes in the end_transaction hook.

We need to call down to the next transaction function when we finish
in linked_attributes.

This also changes linked_attributes to use the common
dsdb_find_dn_by_guid() function

This exposes the linked_attributes to the repl_meta_data module

This came from the linked_attributes module, but now the
repl_meta_data module needs the same functionality, so move it to a
common routine.