It's dangerous if trap handlers are enabled after we already used the
information whether they are enabled or not.
This CL checks for such misbehaviour by remembering whether
{IsTrapHandlerEnabled} was already called, and disallowing
{EnableTrapHandler} afterwards. Also, calling {EnableTrapHandler}
multiple times is disallowed now.

The trap handler tests are changed to only enable trap handlers once,
and to do that before allocating wasm memory or generating code.

R=ahaas@chromium.org

Bug: v8:11017
Change-Id: Ib2256bb8435efd914c12769cedd4a0051052aeef
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2494935Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70750}