pytorch

74a3b9c6 - [fx][acc_tracer] fix defaulted placeholder normalization (#73406)

[fx][acc_tracer] fix defaulted placeholder normalization (#73406) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/73406 Placeholder defaults are stored in `node.args`, during normalization we had dropped these. This diff passes the default args through the normalization transformation. Test Plan: Added tests to cover cases with optional inputs, test covers * nothing passed to optional input * `None` passed to optional input * a tensor passed to optional input Reviewed By: jfix71 Differential Revision: D34463493 fbshipit-source-id: f0c3a4083cb3dd4a69111a758561f0d2c0609787 (cherry picked from commit 7fb482cbfc34077426efa18ac74311bd4533dcdf)