Kotlin, non-builder: chunk redact function every 100 fields

[damianw]

This adds a workaround to an issue discussed in #1448, where the generated redact function is too large to be compiled.

It's much more likely to hit this issue with redact than the other functions because of KT-73789, which results in methods which are significantly longer than necessary specifically due to the repeated ?.let construction.

[oldergod]

thank you for the fix!
I've replaced the test with a golden file which will also confirm compilation is good.
And did a quick refactor so that we clearly see the sequential mutation.

override fun redact(`value`: HundredsFields): HundredsFields {
  var result = redact0(`value`)
  result = redact1(result)
  result = redact2(result)
  return result
}

I thought about writing something like return redact2(redact1(redact0(value)))) but that didn't come as straight forward and I'm sure someone with thousands of fields will say it sucks.