[WIP][Torch] Seeds / Determinism

[VivekPanyam]

This PR implements Torch specific seed and determinism options.

Closes #325

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.42%. Comparing base (30bbdbc) to head (8a6ad22).
⚠️ Report is 122 commits behind head on master.

Files with missing lines	Patch %	Lines
...rce/neuropod/backends/torchscript/torch_backend.cc	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #361      +/-   ##
==========================================
- Coverage   89.45%   89.42%   -0.03%     
==========================================
  Files          57       57              
  Lines        3918     3926       +8     
==========================================
+ Hits         3505     3511       +6     
- Misses        413      415       +2     

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[VivekPanyam]

@selitvin Should we generalize these options more before landing or do you think it's fine to have framework-specific options in RuntimeOptions?

[selitvin]

Should we avoid making these calls all-together is a user opted out to reduce a chance of modifying the default behavior?

[vkuzmin-uber]

My personal perferences:

Even we know that this is for Torch only for now, I would call it: backends_cudnn_deterministic and backends_cudnn_benchmark. And then comment specifies that currently this is Torch only. So, we are going to add more options probably in future and it is better to keep them generic and name accordingly (if only 1 backend supports it - fine, but it helps to see gaps/difference between backends and even can be a start point to add options to other framework.