LG-11454 (1): Add controllers for WebAuthn management

[aduth]

🎫 Ticket

Partially implements LG-11454

🛠 Summary of changes

Adds new Rails controllers for managing WebAuthn authenticators, to be used as part of LG-11454 to manage (rename or delete) an authenticator.

Currently, these routes are accessible but not exposed anywhere within the application. This is split from #9674, in order to reduce the size of that pull request, and to ensure that the routes are available during the 50/50 deployment state for the deploy which would include the frontend interface revisions.

📜 Testing Plan

Ensure build passes.

Optionally, it is expected that the routes for managing an authenticator would be available, including user-facing views and REST API routes. If you know the ID associated with your WebAuthn configuration†, you can visit http://localhost:3000/manage/webauthn/123 (replace the last path portion with ID) to manage the device, which should work as expected.

† You can find this in a rails console as such, replacing the email address with your own:

User.find_with_email('email@example.com').webauthn_configurations.map(&:id)