- Introduces an array of RegisterStates for double registers
- Adds two functions to iterate over the arrays

We will be able to call the ForEach functions using a templated lambda
for RegisterBase<T>.

Bug: v8:7700
Change-Id: I7ef86917d9377933a4bc3456e30de3e4ec547f65
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3596122Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80116}