This is a reland of e13a744a

Fixed jsoncpp BUILD.gn errors by removing missing files.

Original change's description:
> [build] Fix gn check failures in v8/third_party
>
> This removes the blanket exclusion for third_party but leaves
> third_party/icu excluded (which is the same as chrome).
>
> Most fixed issues are to do with previously removed header files and
> missing dependencies.
>
> Bug: v8:7330
> Change-Id: I7e634e35c0620a1f3db9aba01119921e4f781e3e
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2856838
> Auto-Submit: Dan Elphick <delphick@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74295}

Bug: v8:7330
Cq-Include-Trybots: luci.v8.try:v8_linux64_perfetto_dbg_ng
Change-Id: I4c2c63cc3cb6fb3fabe33717b20ac4a1efeec09b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2862772Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74308}