move link_wav.py to paddlespeech/t2s/exps/gan_vocoder/ so that different vocoders can use one script.

* update mb melgan

* update mb melgan, test=tts

* batchsampler or distributebatchsampler

* format

* add style melgan pretraied model

* add style melgan pretraied model, test=tts
Co-authored-by: NHui Zhang <zhtclz@foxmail.com>

* fix logfbank dither

* format

* add hifigan

* add hifigan

* integrate synthesize synthesize_e2e, inference for tts, test=tts

* add some python files, test=tts

* update readme, test=doc_fix

* fix praatio version, test=tts

* fix praatio version, test=tts