Changes to Get span details and correlated OS observability.

the response property details became nullable for the status 400

the response property details became nullable for the status 404

the response property details became nullable for the status 500

the response property payload/input_messages became nullable for the status 200

the response property payload/output_messages became nullable for the status 200

the response property payload/tool_arguments became nullable for the status 200

the response property payload/tool_result became nullable for the status 200

the response property span/allOf[subschema #2]/resource_attributes became nullable for the status 200

the response property span/allOf[subschema #2]/span_attributes became nullable for the status 200

endpoint added