This allows us to roll out the feature to other users. Note that
the flag is also "True" if the user has "webauthn_auth" as their
auth type, so this is compatible with the more fine-grained check
we have on the authentication parts of the feature. We could do a
more explicit "can_use_webauthn or webauthn_auth" check here, but
the idea is that we'll be able to get rid of this flag eventually,
so I've optimised for brevity instead.
I've modified a couple of the unhappy-path tests to make it more
explicit that the flag is false, since it can be true for Platform
Admins and "normal users" alike.
4c2915ce86