[iOS] Implement password picker view

Adds bottom sheet with a table view for choosing credential group to
be shared in the password sharing flow. For now it just displays
username and origin in each row (without favicon) and does not handle
button tap logic.

Bug: 1463882
Change-Id: Ia76e7470fa547bf63cf6deb1d644c3483c5cba9a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4827263
Commit-Queue: Rafał Godlewski <rgod@google.com>
Reviewed-by: Tommy Martino <tmartino@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1191628}