Add aten::slice NNAPI converter (#59364)
Summary:
Add support for aten::slice op in the NNAPI model converter
* If start = 0; end = max -> identity
* Flexible shapes can be passed through
* Flexible shapes can't be sliced over
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59364
Test Plan: pytest test/test_nnapi.py::TestNNAPI::test_slice
Reviewed By: anshuljain1
Differential Revision: D28881039
fbshipit-source-id: 3c1c630ff27b5bba6eda403d87570c61d43ae90e
