IVF supports sampling rates

[xjtushilei]

Is your feature request related to a problem? Please describe.
IVF supports sampling rates. Currently, training and building with all involved is too slow.

Describe the solution you'd like
There are two ways to use this function:

1. Set a quantity n.
2. Set a floating-point ratio f.

Both methods will meet your needs, so you can choose whichever you prefer.

[xjtushilei]

Additional supplement: The training sampling rate of PQ is currently hard-coded to 65536UL, and it is hoped that it can be parameterized.