Instead of passing two bools to the {TaskRunner} constructor, pass to
enums. This makes the semantics more clear in the caller.

In the fuzzer, we actually *do not* want to catch exceptions. This
semantic fix will be done in a follow-up CL, such that this CL is a pure
refactoring.

R=szuend@chromium.org

Bug: v8:11074
Change-Id: I7f6df3a3f344524deb08db10b9317a6734b7ea42
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2526385Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71056}