Allow Service Brokers to indicate if a Service Instance is still usable after a failed update or deprovisioning and if an update can be repeated

[royclarkson]

Add instance_usable and update_repeatable boolean fields to GetLastServiceOperationResponse and ErrorMessage in order to capture the following information. See https://github.com/openservicebrokerapi/servicebroker/blob/v2.16/spec.md#body-1

instance_usable - boolean - If an update or deprovisioning operation failed, this flag indicates whether or not the Service Instance is still usable. If true, the Service Instance can still be used, false otherwise. This field MUST NOT be present for errors of other operations. Defaults to true.

update_repeatable - boolean - If an update operation failed, this flag indicates whether this update can be repeated or not. If true, the same update operation MAY be repeated and MAY succeed; if false, repeating the same update operation will fail again. This field MUST NOT be present for errors of other operations. Defaults to true.