[TTS] Add config and modules for 22khz and 44khz audio codec
# What does this PR do ?

Add config files and corresponding modules for optimized audio codec training.

**Collection**: [TTS]

# Changelog
- Add config files for training 22khz and 44khz audio codec.
- Add inverted HiFiGAN audio encoder
- Add multi resolution STFT discriminator from DAC. This does not make much difference by itself, but I changed in preparation for doing mixed bandwidth training.
- Added a "half snake" activation to decoder which uses half snake and half leaky relu activations, allowing the model to jointly model both periodic and non-periodic information. When tuning hyperparameters, I found this to be more stable (and use less memory) than training with all snake activations. And perform better than using the existing _snake alpha_, and had similar performance to the _snake beta_ variants from BigVGAN 1 and 2. I did not add snake activation to encoder as doing so significantly reduced TTS performance on the codec.
- Replaced tanh activation on output with clamping, as in BigVGAN 2, as this seemed to reduce artifacts early in training.

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