[WebAuthn] Display passkey username in confirmation saved bubble

Additionally adds a different version of a title (with "and PIN
created") for cases where GPM Pin was created during the passkey
creation flow.

Stores those two bits (username, gpm_pin_created) in manage passwords
state. Updates APIs to pass that in OnPasskeySaved() and from manage
passwords controller to passkey saved confirmation controller.

Bug: b/345242100
Change-Id: Ic8dcdc7e48ca4a6896471eb1378e95aceb062af2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5648027
Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Rafał Godlewski <rgod@google.com>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1317969}