Implement swipe to dismiss in the card unmask authentication selection on iOS.

When unmasking payment cards: Before, the authentication selection sheet
could be dismissed by swiping; however, this did not stop the
coordinator for the card unmasking flow. Now, swiping the sheet stops
the coordinator (and also logs metrics, the same as tapping the cancel
button.)

Bug: 40282545, b/324886800
Change-Id: If28ec268995d5a55dccce25c9d0d286ceeb9ddde
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5422788


Reviewed-by: Siyu An <siyua@chromium.org>
Reviewed-by: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Slobodan Pejic <slobodan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1283377}