We often want to pass a list of moves of fixed length. Instead of
constructing an array on the caller's stack and passing it via
{ArrayVector}, we should just pass it via {std::initializer_list}. This
also avoids to spell out the internal name
{LiftoffAssembler::ParallelRegisterMoveTuple}.

R=thibaudm@chromium.org

Bug: v8:10576
Change-Id: Ibe7ac5a5a02686533333cb45652cbb2b99ad9c60
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2287498
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68799}