Add interface/object serialization as module attribute (#26770)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26770
This PR added the interface/object serialization as module attribute, to
allow initializing object as a interface type during python
initialization. Because interface type can be backed by any class object
that implements that interface, if we declare it in
python/module.__init__, we will need to collect the run time types of the
value and serialize them to ensure complete code information
Test Plan: Imported from OSS
Differential Revision: D17742707
fbshipit-source-id: 7f614ad4f982996d320a0e2dd3515bf47370e730
