Allow any input in to_onnx and to_torchscript (#4378)

* branch merge

* sample

* update with valid input tensors

* pep

* pathlib

* Updated with BoringModel and added more input types

* try fix

* pep

* skip test with torch < 1.4

* fix test

* Apply suggestions from code review

* update tests

* Allow any input in to_onnx and to_torchscript

* Update tests/models/test_torchscript.py

Co-authored-by: Adrian Wälchli <aedu.waelchli@gmail.com>

* no_grad

* try fix random failing test

* rm example_input_array

* rm example_input_array

Co-authored-by: chaton <thomas@grid.ai>
Co-authored-by: Jeff Yang <ydcjeff@outlook.com>
Co-authored-by: Roger Shieh <sh.rog@protonmail.ch>
Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: Adrian Wälchli <aedu.waelchli@gmail.com>
Co-authored-by: edenlightning <66261195+edenlightning@users.noreply.github.com>