[webauthn] Add automaticPresenceSimulation to DevTools Protocol.

This patch adds an `automaticPresenceSimulation` option to the WebAuthn
DevTools protocol. The option allows controlling whether authenticators
simulate passing or failing tests of user presence.

This is one in a series of patches intended to create a Testing API for
WebAuthn, for use in Web Platform Tests and by external webauthn tests.

For an overview of overall design, please see
https://docs.google.com/document/d/1bp2cMgjm2HSpvL9-WsJoIQMsBi1oKGQY6CvWD-9WmIQ/edit?usp=sharing

Bug: 922572
Change-Id: Id8e60c83dd3ca9ab7ff659e8a2c1f765bd60690b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660256
Commit-Queue: Nina Satragno <nsatragno@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#669711}
16 files changed