[jit] Module clone work with shared ClassType (#31970)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31970
Now that the ClassType can be shared among different module instances, we'll
preserve the sharing in clone as well, that is if the original module has
a ClassType that is shared, we'll clone this ClassType once and share it between
different module instances as well.
Test Plan:
build/test/test_jit
Imported from OSS
Differential Revision: D19406251
fbshipit-source-id: 2881c695f6e718e5432040a3817cf187a62017bf
