support rewind in DTS (#60)

* add fields for implementing suborchestration rewind in DTS

* tags are now being added to SubOrchestrationInstanceCreatedEvent in DurableTask.Core, so they are not backend-specific anymore

Author: sebastianburckhardt

protos/orchestrator_service.proto

@@ -115,6 +115,7 @@ message SubOrchestrationInstanceCreatedEvent {
     google.protobuf.StringValue version = 3;
     google.protobuf.StringValue input = 4;
     TraceContext parentTraceContext = 5;
+    map<string, string> tags = 6;
 }
 
 message SubOrchestrationInstanceCompletedEvent {
@@ -225,6 +226,11 @@ message ExecutionRewoundEvent {
     google.protobuf.StringValue parentExecutionId = 2; // used only for rewinding suborchestrations, null otherwise
     google.protobuf.StringValue instanceId = 3; // used only for rewinding suborchestrations, null otherwise
     TraceContext parentTraceContext = 4; // used only for rewinding suborchestrations, null otherwise
+    google.protobuf.StringValue name = 5; // used by DTS backend only
+    google.protobuf.StringValue version = 6; // used by DTS backend only
+    google.protobuf.StringValue input = 7;  // used by DTS backend only
+    ParentInstanceInfo parentInstance = 8; // used by DTS backend only
+    map<string, string> tags = 9; // used by DTS backend only
 }
 
 message HistoryEvent {