Changes to Upsert an activity record

the code response's property type changed from string to no type for status 409

added subschema #1 subschema #2 subschema #3 to the code response property anyOf list for the response status 409

added subschema #5 subschema #6 subschema #7 to the code response property anyOf list for the response status 400

removed the concurrent_write_conflict enum value from the code response property for the response status 409

endpoint added