Fix cache aware hybrid bugs
# What does this PR do ?

Fixes some bugs to support Hybrid and FastConformer variants of cache-aware streaming models.

# Changelog 
- Fixed a bug which prevented switching between decoders for Hybrid models
- Added support of Hybrid models to the cache-aware streaming inference scripts
- Added the feature to switch between decoders to the cache-aware streaming simulation script
- Added support of causal downsamling for dw_striding approach.

# Usage
Users may use the --set_decoder "rnnt" or "ctc" to change the decoder with speech_to_text_cache_aware_streaming_infer.py.
They may use asr_model.change_decoding_strategy(decoder_type='ctc' or 'rnnt') to change the decoding for a Hybrid model in general.

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