[FX][EZ] Allow constructing GraphModule with dict for root (#44679)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44679
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D23696766
Pulled By: jamesr66a
fbshipit-source-id: fe18b7b579c1728d00589bd5fd5e54c917cc61fe
