pretty printing

[DonAurelio]

Added pretty-print support for the pytorch backend's iprof -t trace mode.

$ iprof --backends pytorch -t -- python3 pytorch_example.py
THAPI: Trace location: /home/user/thapi-traces/thapi--...
12:48:41.465852539 - aurora-uan-0010 - vpid: 1356307, vtid: 1356307 - lttng_ust_pytorch:op_entry: { name: "aten::empty\x00", overload_name: "memory_format\x00" }
12:48:41.465936501 - aurora-uan-0010 - vpid: 1356307, vtid: 1356307 - lttng_ust_pytorch:op_exit: { name: "aten::empty\x00", overload_name: "memory_format\x00" }

[TApplencourt]

"aten::empty\x00" pretty print hsould not print \x00 AFAIK.
Does other backend print the last \x00?

[TApplencourt]

FOr historical reason, pretty print use this pattern for testing:
https://github.com/argonne-lcf/THAPI/tree/devel/backends/itt/tests