repr and _*state_dict for qRNN (#31540)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31540
Fixes #31468
Test Plan: Imported from OSS
Differential Revision: D19205894
Pulled By: z-a-f
fbshipit-source-id: 80c36f74aa20a125ea8d74a54e9905576f1bc6d7
