[iOS] Modify content notifications toggle to become a detailItem.

This change modifies the existing content notifications toggle on the
notification settings tab to become a detailItem, that when clicked will
open the content notifications view controller.

This CL also adds functionality to be able to change symbol tints for detailItems.

Bug: b/324443743
Change-Id: Ie4e22ddb0dd9056b0cf32874ebe824897ba5584a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5310775


Reviewed-by: Marke Hallowell <wry@chromium.org>
Commit-Queue: Guillem Perez <guiperez@google.com>
Auto-Submit: Guillem Perez <guiperez@google.com>
Cr-Commit-Position: refs/heads/main@{#1264066}