[DiffSinger] Add more mel checks between vocoder and acoustic model

[yqzhishen]

The following checks are performed between DiffSinger vocoder and acoustic model:

• sample_rate, hop_size, num_mel_bins, mel_fmin, mel_fmax must be equal
• mel_scale must be equal and must be slaney or htk
• mel_base must be 10 or e (mel will be transformed between mismatching values)