Update on "Serializing from_node info in et serializer"

We need to use the from_node informaton in deserialzied exported graph for operator tracing in et.inspector.  this diff updates the serizalier to support serde from_node info.

Differential Revision: [D78293986](https://our.internmc.facebook.com/intern/diff/D78293986/)

[ghstack-poisoned]

Author: Gasoonjia