cr_fuchsia_package is deprecated in favor of using the Fuchsia
SDK provided rules directly.

This CL adds a cmx file specifically for v8_unittests. CMX
files define fuchsia components, see
https://chromium-review.googlesource.com/c/chromium/src/+/3529652
for more info.

Bug: chromium:1092804
Change-Id: Ibf1d866ec6b94a0e1a7a7c7c443a6ee80e3b1042
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3537885Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Bryant Chandler <bryantchandler@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79760}