[MXNET-1252][1 of 2] Decouple NNVM to ONNX from NNVM to TenosrRT conv…

[haohuanw]

Description

This PR is the first step for [MXNET-1252]. The goal for this PR is to change the dependency tree from "nnvm_to_onnx -> tensorrt" to "tensorrt -> nnvm_to_onnx". This enables the possibility of converting nnvm to other inference library.

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [MXNET-$JIRA_ID], where $JIRA_ID refers to the relevant JIRA issue created (except PRs with tiny changes)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Unit tests are added for small changes to verify correctness (e.g. adding a new operator)
• Nightly tests are added for complicated/long-running ones (e.g. changing distributed kvstore)
• Build tests will be added for build configuration changes (e.g. adding a new build option with NCCL)
• Code is well-documented:
• For user-facing API changes, API doc string has been updated.
• For new C++ functions in header files, their functionalities and arguments are documented.
• For new examples, README.md is added to explain the what the example does, the source of the dataset, expected performance on test set and reference to the original paper if applicable
• Check the API doc at https://mxnet-ci-doc.s3-accelerate.dualstack.amazonaws.com/PR-$PR_ID/$BUILD_ID/index.html
• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

Changes

• NNVM to TRT: ran unit tests: tests/python/tensorrt

Comments

• This is not a backward incompatible change; all changes are internal

[haohuanw]

looks like cpplint failed, will work on that.

[Roshrini]

@mxnet-label-bot Add [pr-awaiting-testing]

[haohuanw]

edge failed probably due to: #13665

[KellenSunderland]

Can you rebase? Edge should be fixed now.

[KellenSunderland]

LGTM