bert_module: fix inputs of export model
Exported ONNX model had to be passed with "attention_mask" and
"token_type_ids" inputs swapped to get correct output.

Changing the input order fixes this issue.
Also return a dict instead of list for correctly passing inputs.

# What does this PR do ?

Fix swapped model inputs for exported ONNX/TRT model.

**Collection**: NLP

# Changelog 
- Fix order of inputs returned via input_types()

# Usage
* You can potentially add a usage example below

```python
# Add a code snippet demonstrating how to use this 
```

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- [x] Make sure you read and followed [Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md)
- [x] Did you write any new necessary tests? - Updated related tests.
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  - [ ] Reviewer: Does the PR have correct import guards for all optional libraries?
  
**PR Type**:
- [x] Bugfix

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## Who can review?
@MaximumEntropy, @ericharper, @ekmb, @yzhang123

Anyone in the community is free to review the PR once the checks have passed. 
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# Additional Information
* Related to # (issue)
