Add request/response thrift types for start workflow http endpoint (#729)

## Summary
Needed for orchestration service till we move over these thrift files

## Checklist
- [ ] Added Unit Tests
- [ ] Covered by existing CI
- [ ] Integration tested
- [ ] Documentation update



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced support for starting workflows with detailed parameters,
including node name, branch, date range, and partition specifications.
- Responses now include the workflow identifier when a workflow is
started.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: kumar-zlai

api/thrift/orchestration.thrift

@@ -256,6 +256,19 @@ struct UploadResponse {
     1: optional string message
 }
 
+struct WorkflowStartRequest {
+    1: optional string nodeName
+    2: optional string branch
+    3: optional string startDate
+    4: optional string endDate
+    5: optional string partitionSpecFormat
+    6: optional i64 partitionSpecMillis
+}
+
+struct WorkflowStartResponse {
+    1: optional string workflowId
+}
+
 // ====================== End of Orchestration Service API Types ======================
 
 /**