This CL refactors mjsunit tests, so that the common core of all tests is
abstracted away.

Bug: v8:11525, v8:11706
Change-Id: I24a1af4298380e21a64e4d17149422c32fbf8a4d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2914882Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Vicky Kontoura <vkont@google.com>
Cr-Commit-Position: refs/heads/master@{#74853}