[Autofill Payments] Updating UnmaskRequest to include FIDO Assertion Info.

This CL allows for a payments request to include a FIDO assertion response instead of a CVC to unmask a credit card.

Bug: 949269
Change-Id: Icdae1023f8b9f3eac1e6e19b595990229a3f9236
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1623920
Reviewed-by: Jared Saul <jsaul@google.com>
Commit-Queue: Manas Verma <manasverma@google.com>
Cr-Commit-Position: refs/heads/master@{#668442}