[iOS][stts-notifs] Add long press menu with hide action for STTS module

This CL adds the long-press context menu with a hide action for the
STTS magic stack module.

Using a pref to persist the "disabled" state is not necessary for this
module since it can only be shown once.

Low-Coverage-Reason: TESTS_IN_SEPARATE_CL
Bug: 343495516
Change-Id: Ib0678ec7984a039bbaa759fbc4a021a6a88bc66c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5952949
Commit-Queue: Hira Mahmood <hiramahmood@google.com>
Reviewed-by: Scott Yoder <scottyoder@google.com>
Cr-Commit-Position: refs/heads/main@{#1374099}