This CL moves the two remaining IC stubs to builtins, generating a
dedicated builtin for each KeyedAccessStoreMode variant.

Bug: v8:7777
Change-Id: I540b3c3437adb94094771a19713e71ec8a349553
Reviewed-on: https://chromium-review.googlesource.com/c/1346095Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57719}