Spanify `RedactionTool` (2/2)

Convert `kBuiltInFirstPartyExtensionIds` to an array of
`std::string_view` and tweak functions as necessary.

Change the business logic to not expect a `nullptr` sentinel.

Fixed: 439455382
Change-Id: Ia79513fee6503c41b91726f2391f2d18c0a5267d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7544239
Reviewed-by: Xiangdong Kong <xiangdongkong@google.com>
Auto-Submit: Kalvin Lee <kdlee@chromium.org>
Commit-Queue: Kalvin Lee <kdlee@chromium.org>
Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1587695}
NOKEYCHECK=True
GitOrigin-RevId: edc4b56703ff9cb7bf14c95d72aa3b8efb98c305