Batch request may fail because of return=minimal header

[dogukan10]

Some fhir repositories such as Firely Server does not support return=minimal header for batch requests.

In this case, we get an java.lang.ClassCastException in parseEntryAsResponse function: https://github.com/srdc/onfhir/blob/master/onfhir-common/src/main/scala/io/onfhir/api/client/FHIRBundle.scala#L212 since the response includes an OperationOutcome, indicating that return=minimal header is not supported on interaction the system_batch, which has no response field.