Adding retry logic to the TritonInferenceStage to allow recovering from errors

[cwharris]

Factor out the Triton inference logic in the Triton inference stage to a client class which can be swapped out for a fake/test client. Keep retry logic in the Stage and test using a fake/test client.

Closes #1510

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• I am familiar with the Contributing Guidelines.
• When the PR is ready for review, new or existing tests cover these changes.
• When the PR is ready for review, the documentation is up to date with these changes.

[mdemoret-nv]

/merge