1. Move the reading of Notation before calling
   SetNumberFormatDigitOptions()
   ( sync after https://github.com/tc39/proposal-unified-intl-numberformat/pull/37)
2. Sync SetNumberFormatDigitOptions to the spec.
3. Consider the case that while RoundingType is "compact-rounding"
   do not set the precision.
4. correct the tests accordingly.
5. Fix the rounding of notation: "compact" and put regression cases
   into test/intl/regress-9408.js

Bug: v8:9408
Change-Id: I78d66601fe21b1a74a50047b2abe6a2838a58b8c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1681599
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62450}