LUCENE-10319: make ForUtil#BLOCK_SIZE changeable

[gf2121]

In LUCENE-10315, I tried to generate a ForUtil whose BLOCK_SIZE=512, I thought it could be simple since it looks like i only need to change the BLOCK_SIZE, but it turns out that there are a lot of hard code values...

So this is trying to make all hard code value generated from the BLOCK_SIZE in case we need a ForUtil somewhere else or want to change BLOCK_SIZE in postings in feature.

I tried to make the BLOCK_SIZE = 64 / 256 and all tests passed.

[jpountz]

I'm a bit torn as this also makes the code harder to read with all these constants with complex names.

[gf2121]

Thanks @jpountz ! This is indeed making codes harder to read. I tried to make all these complex constants generated from script, keeping ForUtil.java clean. How does it look now?

[gf2121]

Let these codes be generated from the script, so that it can change with the change of BLOCK_SIZE.