The CL does the following:
1) Globalizes CagedHeap for all HeapBases;
2) Adds the global variable representing the cage base;
3) Changes all write-barriers to use this global variable for value/slot
   checks;
4) Removes no longer needed functionality introduced in previous CLs.

Bug: v8:12231
Change-Id: I281a7b0bf67e349c988486fc2d43ec6d703fd292
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3688050
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81027}