Introduce a new annotation @customCppClass that can be used for
non-extern @export classes, that is, generate everything, remove
boilerplate from all the internal lists and switches, but allow
a custom C++ class, which in turn also allows overwriting the generated
print and verify functions.

Port DescriptorArray and StrongDescriptorArray as an example.

Bug: v8:7793
Change-Id: I744e52fb4102ac49c0097f1c95bb17d301975bf0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2489687Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70989}