Refs #34429: Following the implementation allowing the setting of
unusable passwords via the admin site, the `BaseUserCreationForm` and
`UserCreationForm` were extended to include a new field for choosing
whether password-based authentication for the new user should be enabled
or disabled at creation time.
Given that these forms are designed to be extended when implementing
custom user models, this branch ensures that this new field is moved to
a new, admin-dedicated, user creation form `AdminUserCreationForm`.
Regression in e626716c28.
Thanks Simon Willison for the report, Fabian Braun and Sarah Boyce for
the review.
0ebed5fa95