Adjust condition for initializing chasm tree root for new workflows (#8638)

## What changed?
Changed the condition to check whether the root component of the chasm
tree has been initialized for new workflows

## Why?
The root component is never actually empty since we are using
`NewEmptyTree` which sets a root component with no type

## How did you test it?
- [x] built
- [ ] run locally and tested manually
- [ ] covered by existing tests
- [ ] added new unit test(s)
- [ ] added new functional test(s)

Author: pdoerner

chasm/tree.go

@@ -1174,7 +1174,7 @@ func unmarshalProto(
 
 	value := reflect.New(valueT.Elem())
 
-	if dataBlob == nil {
+	if dataBlob == nil || len(dataBlob.Data) == 0 {
 		// If the original data is the zero value of its type, the dataBlob loaded from persistence layer will be nil.
 		// But we know for component & data nodes, they won't get persisted in the first place if there's no data,
 		// so it must be a zero value.

service/history/workflow/mutable_state_impl.go

@@ -2589,9 +2589,7 @@ func (ms *MutableStateImpl) ApplyWorkflowExecutionStartedEvent(
 		root, ok := ms.chasmTree.(*chasm.Node)
 		softassert.That(ms.logger, ok, "chasmTree cast failed")
 
-		validationContext := chasm.NewContext(context.Background(), root)
-		_, err := root.Component(validationContext, chasm.ComponentRef{})
-		if common.IsNotFoundError(err) {
+		if root.Archetype() == "" {
 			mutableContext := chasm.NewMutableContext(context.Background(), root)
 			root.SetRootComponent(chasmworkflow.NewWorkflow(mutableContext, ms))
 		}