[iOS][Bookmarks] Rename functions.

Those functions are only used to edit bookmarks, and not to add them.
This name clarifies it.

Bug: none
Change-Id: I0f0781f527ac85dfe75fe13b1728289e8858a03a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5233530
Commit-Queue: Arthur Milchior <arthurmilchior@chromium.org>
Reviewed-by: Tanmoy Mollik <triploblastic@google.com>
Cr-Commit-Position: refs/heads/main@{#1252010}