Refactor the {options} output parameter of the fast callback to a
reference, since it can never be nullptr for functions created with
MakeWithFallbackSupport. This allows embedders to spare the nullptr
check.

Bug: chromium:1052746
Change-Id: I3e22f07af4740ebe8522691da51b6addbc980f24
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2491026Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70706}