- Removes kPadArguments boolean.
- Changes ShouldPadArguments to ArgumentPaddingSlots to reflect
  that on some architectures more than 1 padding slot may be needed.
- Adds AddArgumentPaddingSlots and ShouldPadArguments convenience
  functions.

Bug: v8:9198

Change-Id: Iba87518e071a75fb951b490d3f75a87ca715cc23
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2679109
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72605}