This is a reland of 811bfbbc

Original change's description:
> [regexp] Move AST-to-Node code to a dedicated file
>
> Prior to this CL, jsregexp contains a bunch of things that are slightly
> related but would be cleaner in separate files, including: AST-to-Node
> transformations, the compiler implementation, and a debugging printer.
>
> This CL extracts AST-to-Node transformations.
>
> Bug: v8:9359
> Change-Id: I030cfca5c40cfd72e3a7abe2188e4654cfe2277c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1655303
> Auto-Submit: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62148}

Tbr: yangguo@chromium.org
Bug: v8:9359
Change-Id: I68a16086dc56c9a059547033ca8bc1e9de1080db
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1658568Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62154}