Add _get_type() API to RRef (#44663)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44663
The new API returns the type of the data object referenced by this
`RRef`. On the owner, this is same as `type(rref.local_value())`.
On a user, this will trigger an RPC to fetch the `type` object from
the owner. After this function is run once, the `type` object is
cached by the `RRef`, and subsequent invocations no longer trigger
RPC.
closes #33210
Test Plan: Imported from OSS
Reviewed By: rohan-varma
Differential Revision: D23691990
Pulled By: mrshenli
fbshipit-source-id: a2d87cd601a691dd75164b6bcd7315245e9cf6bd
