[iOS][Translate] Adds auto-always/auto-never translate functionality to iOS

- Moves the logic to determine whether "Always Translate Language" and
  "Never Translate Language" should automatically trigger from Android's
  translate infobar to TranslateInfobarDelegate to share with iOS.
- Adds the logic to trigger Snackbars notifications for these events.

Bug: 910994
Change-Id: Iccfe36387eda6fd2377c35b200178c5e31a26521
Reviewed-on: https://chromium-review.googlesource.com/c/1443312
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Reviewed-by: anthonyvd <anthonyvd@chromium.org>
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628969}
7 files changed