core: Populate Dependencies of ResourceInstanceObject during apply

Previously we kept the dependencies one level higher on the resource
instance itself, which meant that updating it was handled in a different
EvalNode, but now we consider these to be dependencies of the object
itself (derived from the configuration that was current at the time it
was created), so we must handle this during EvalApply.

The subtle difference here is that if an object is moved to "deposed"
during a create_before_destroy replace then it will retain the
dependencies it had on its last apply, rather than them being replaced
by the dependencies of the newly-created object.

terraform/eval_apply.go

@@ -20,6 +20,7 @@ import (
 type EvalApply struct {
 	Addr           addrs.ResourceInstance
 	Config         *configs.Resource
+	Dependencies   []addrs.Referenceable
 	State          **states.ResourceInstanceObject
 	Change         **plans.ResourceInstanceChange
 	ProviderAddr   addrs.AbsProviderConfig
@@ -171,7 +172,7 @@ func (n *EvalApply) Eval(ctx EvalContext) (interface{}, error) {
 			Status:       states.ObjectReady, // TODO: Consider marking as tainted if the provider returned errors?
 			Value:        newVal,
 			Private:      resp.Private,
-			Dependencies: nil, // not populated here; this will be mutated by a later eval step
+			Dependencies: n.Dependencies, // Should be populated by the caller from the StateDependencies method on the resource instance node
 		}
 	}
 

terraform/node_resource_apply_instance.go

@@ -332,6 +332,7 @@ func (n *NodeApplyableResourceInstance) evalTreeManagedResource(addr addrs.AbsRe
 			&EvalApply{
 				Addr:           addr.Resource,
 				Config:         n.Config,
+				Dependencies:   n.StateReferences(),
 				State:          &state,
 				Change:         &diffApply,
 				Provider:       &provider,