Add tests for internal external uncached strings with cacheable
resources, for the cached_data functionality added in
https://chromium-review.googlesource.com/c/v8/v8/+/2710440.

Bug: v8:7790, v8:11463
Change-Id: I679c50995d315cc4289452a00838b3cafa4c93e4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2715187Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73103}