Refactor snapshot flow for slot based snapshotting (#974)

This lays the ground work for cases where we want a consistent view
without creating a slot by exposing a transaction snapshot

flow/workflows/snapshot_flow.go

@@ -222,6 +222,27 @@ func (s *SnapshotFlowExecution) cloneTables(
 	return nil
 }
 
+func (s *SnapshotFlowExecution) cloneTablesWithSlot(
+	ctx workflow.Context,
+	sessionCtx workflow.Context,
+	numTablesInParallel int,
+) error {
+	logger := s.logger
+	slotInfo, err := s.setupReplication(sessionCtx)
+	if err != nil {
+		return fmt.Errorf("failed to setup replication: %w", err)
+	}
+
+	logger.Info("cloning tables in parallel: ", numTablesInParallel)
+	s.cloneTables(ctx, slotInfo, numTablesInParallel)
+
+	if err := s.closeSlotKeepAlive(sessionCtx); err != nil {
+		return fmt.Errorf("failed to close slot keep alive: %w", err)
+	}
+
+	return nil
+}
+
 func SnapshotFlowWorkflow(ctx workflow.Context, config *protos.FlowConnectionConfigs) error {
 	logger := workflow.GetLogger(ctx)
 
@@ -271,21 +292,8 @@ func SnapshotFlowWorkflow(ctx workflow.Context, config *protos.FlowConnectionCon
 	}
 	defer workflow.CompleteSession(sessionCtx)
 
-	slotInfo, err := se.setupReplication(sessionCtx)
-	if err != nil {
-		return fmt.Errorf("failed to setup replication: %w", err)
-	}
-
-	if slotInfo == nil {
-		logger.Info("no slot info returned, skipping qrep workflow")
-		return nil
-	}
-
-	logger.Info("cloning tables in parallel: ", numTablesInParallel)
-	se.cloneTables(ctx, slotInfo, numTablesInParallel)
-
-	if err := se.closeSlotKeepAlive(sessionCtx); err != nil {
-		return fmt.Errorf("failed to close slot keep alive: %w", err)
+	if err := se.cloneTablesWithSlot(ctx, sessionCtx, numTablesInParallel); err != nil {
+		return fmt.Errorf("failed to clone slots and create replication slot: %w", err)
 	}
 
 	return nil