[torch] Add debug name to assert message for useOf
Summary:
Make an assert message in Pytorch's JIT provide better information by
printing the debug name of a value in `PythonPrintImpl::useOf` if it's not
found in any tables.
Test Plan:
Tested printing a `module.code` where the module had an invalid value used
as an operand. Before it asserted without any more details, afterwards it
printed the debug name which made it easy to track down the offending value.
Reviewed By: SplitInfinity
Differential Revision: D28856026
fbshipit-source-id: 479f66c458a0a2d9a161ade09f20382e7b19d60e
