Add _set_instance_obj_error_state() to compute manager

This provides an object-aware analog to the existing function,
which operates on an object instead of using a uuid and the
conductor instance update path.

Over time, we should be able to transition all existing uses to
this function, and then remove the old implementation.

Related to blueprint compute-api-objects

Change-Id: I781eadfb01a13bab9337ec05653a4780447731b8
Merge "Add _set_instance_obj_error_state() to compute manager"