Update TTS Dataset, FastPitch with TTS dataset and small improvements in HiFiGAN
* Update TTSDataset to use speaker id
* Update FastPitch to use new TTS Dataset 
* Update HiFiGAN (more flexible `configure_optimizers`) and rename generator config for 44100 khz (it is just extended v1, but for 44100, it shouldn't be v4, IMO)


Signed-off-by: Oktai Tatanov <oktai.tatanov@gmail.com>