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* Get rid of sine wave files and whitenoise files
* Refactor integer encoding
* Relax rtol from 1e-8 to 1e-7 for compliance kaldi
* relax waveform multi channel resample atol to 1e-7 from 1e-8
* relax tolerance for length consistency for speed effect
Co-authored-by: moto <855818+mthrok@users.noreply.github.com>

* Add sox_utils module

* Make init/shutdown thread safe

* Add sox effects implementation

* Add test for sox effects

* Update docstrings and add examples

This PR replaces `torchaudio.sox_effects.SoxEffectsChain` in `test_sox_compatibility` with bare `sox` command.

The parity of `torchaudio.sox_effects.SoxEffectsChain` against `sox` command is not tested and it has known issues https://github.com/pytorch/audio/issues/771, therefore it is not appropriate to use this class for testing other functions.

Part of #764

 - Replace `whitenoise.wav` with on-the-fly data generation
 - Replace `torchaudio.load` with `common_utils.load_wav`
 - Replace `steam-train-whistle-daniel_simon.mp3` with `.wav`