Batch operation rate limit (#318)

## What changed?

Adding (optional) max_operations_per_second for batch operations to limit their rate.

## Why?

To fix temporalio/temporal#4926.

temporal/api/workflowservice/v1/request_response.proto

@@ -1242,15 +1242,22 @@ message StartBatchOperationRequest {
     // Namespace that contains the batch operation
     string namespace = 1;
     // Visibility query defines the the group of workflow to apply the batch operation
-    // This field and Executions are mutually exclusive
+    // This field and `executions` are mutually exclusive
     string visibility_query = 2;
     // Job ID defines the unique ID for the batch job
     string job_id = 3;
     // Reason to perform the batch operation
     string reason = 4;
     // Executions to apply the batch operation
-    // This field and VisibilityQuery are mutually exclusive
+    // This field and `visibility_query` are mutually exclusive
     repeated temporal.api.common.v1.WorkflowExecution executions = 5;
+    // Limit for the number of operations processed per second within this batch.
+    // Its purpose is to reduce the stress on the system caused by batch operations, which helps to prevent system
+    // overload and minimize potential delays in executing ongoing tasks for user workers.
+    // Note that when no explicit limit is provided, the server will operate according to its limit defined by the
+    // dynamic configuration key `worker.batcherRPS`. This also applies if the value in this field exceeds the
+    // server's configured limit.
+    float max_operations_per_second = 6;
     // Operation input
     oneof operation {
         temporal.api.batch.v1.BatchOperationTermination termination_operation = 10;