Add experimental MPS device support for ASR inference
# What does this PR do ?

Add support for MPS device (Apple Silicon M-series GPU) for ASR inference

**Collection**: [ASR]

# Changelog 
- allow to select MPS device in `transcribe_speech.py`

# Usage

MPS device will be automatically selected in `transcribe_speech.py` or `speech_to_text_eval.py` if `allow_mps=true` flag is explicitly set, and MPS device is available.
Will work only with PyTorch >= 2.0, for now env variable `PYTORCH_ENABLE_MPS_FALLBACK=1` should be set.

Tested with models:
- https://catalog.ngc.nvidia.com/orgs/nvidia/teams/nemo/models/stt_en_conformer_ctc_large
- https://catalog.ngc.nvidia.com/orgs/nvidia/teams/nemo/models/stt_en_conformer_transducer_large

```shell
PYTORCH_ENABLE_MPS_FALLBACK=1 python examples/asr/transcribe_speech.py \
    allow_mps=true \
    <other script params>

PYTORCH_ENABLE_MPS_FALLBACK=1 python examples/asr/speech_to_text_eval.py \
    allow_mps=true \
    <other script params>
```


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**PR Type**:
- [x] New Feature
- [ ] Bugfix
- [ ] Documentation

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# Additional Information
* Related to # (issue)
