[iOS] [byot] Implement methods in bring_android_tabs_util.mm

This CL implements the methods declared in bring_android_tabs_util.h.
Unit test support will come in a later CL.

dd: go/bring-android-tabs-dd

Bug: 1418114
Change-Id: I4fc2f3d88d25dbd7d29e3ef8983b01ce69e80c36
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4342032


Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Ginny Huang <ginnyhuang@chromium.org>
Commit-Queue: Hira Mahmood <hiramahmood@google.com>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Siddhartha S <ssid@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1120042}