[jit] tracer flag to guard risky behaivors (#36277)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36277
This PR introduce a flag to the tracer that guard the risky behaviors
like adding list/dict as output of the tracer. Currently to ensure not
BC breaking user, we throw warning if the tracer output is list, and
will throw error when the tracer output is dict to enforce using this
flag (next PR)
Test Plan: Imported from OSS
Differential Revision: D20998157
Pulled By: wanchaol
fbshipit-source-id: 0d2c55f1a263a48b1b92dd6ad54407815e0a6f72
