Don't call get on context if not a dict

With ironic we have a case where context is a RequestContext but this
context object doesn't have the original_resources attribute. In this
case we're proceeding into else, call get() on context, which
RequestContext does not have either and run into

AttributeError: 'RequestContext' object has no attribute 'get'

To guard against this we're now only calling get() on context if it
explicitly is a dict. If none can be found we just don't have any
original_resources. The only case where this logic will break is if we
have cases where we have a context object that doesn't have a
original_resources attribute, is not a dict but SOMEHOW provides a get()
method that would provide the original_resources when provided as a
string argument (which I don't think is very likely).

Author: sebageek

auditmiddleware/_api.py

@@ -543,7 +543,7 @@ def _create_cadf_event(self, project, res_spec, res_id, res_parent_id,
             original_resources = []
             if hasattr(context, 'original_resources'):
                 original_resources = context.original_resources
-            else:
+            elif isinstance(context, dict):
                 original_resources = context.get('original_resources', [])
 
             # If we found original_resources and it's a list, get project_id