[ios] Request expiration date as for expired cards in CVC prompt

This patch fixes a bug in the Card Verification Code prompt for
autofill. When the user wants to autofill a credit card already saved
in their profile, the CVC prompt is displayed. If the card is already
expired, they need to enter the new CVC and expiration date through
the prompt. The bug was about not requesting the expiration date right
away, so users would enter a CVC, the verification would fail and then
the expiration date would be required. The patch checks for expired
cards when the CVC prompt is presented and requires expiration date
accordingly. A unit test verifies the state of the prompt for expired
cards.

A minor refactoring was also needed to focus on the right field( expiration date or cvc ) after each UI transition.

Bug: 1472722
Change-Id: I2f820ac36c503b503dc965d478e4ac253463dc42
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4864459
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Commit-Queue: Ernesto Izquierdo Clua <eic@google.com>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1197814}