fix(setup): Zope root cookie auth and login form

[rpatterson]

The GenericSetup "various" import step that originally installs PAS into a Plone portal
also migrates the Zope root /acl_users. Probably an accident over time, but it
results in a cookie auth plugin that doesn't work outside of the Plone portal:

2021-12-27 11:12:02,243 ERROR   [Zope.SiteErrorLog:22][waitress-0] ComponentLookupError: http://localhost:49080/api/acl_users/credentials_cookie_auth/login
Traceback (innermost last):
  Module ZPublisher.WSGIPublisher, line 162, in transaction_pubevents
  Module ZPublisher.WSGIPublisher, line 372, in publish_module
  Module ZPublisher.WSGIPublisher, line 266, in publish
  Module ZPublisher.mapply, line 85, in mapply
  Module ZPublisher.WSGIPublisher, line 63, in call_object
  Module Products.PlonePAS.plugins.cookie_handler, line 106, in login
  Module Products.PluggableAuthService.PluggableAuthService, line 1153, in updateCredentials
  Module Products.PlonePAS.plugins.cookie_handler, line 74, in updateCredentials
  Module zope.component._api, line 165, in getUtility
zope.interface.interfaces.ComponentLookupError: (<InterfaceClass plone.registry.interfaces.IRegistry>, '')

This import step also removes the login_form template which breaks the challenge
response.

Add an interface check to decide whether to install Plone's ExtendedCookieAuthHelper
or PAS's vanilla CookieAuthHelper.

[mister-roboto]

@rpatterson thanks for creating this Pull Request and help improve Plone!

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass.

Whenever you feel that the pull request is ready to be tested, either start all jenkins jobs pull requests by yourself, or simply add a comment in this pull request stating:

@jenkins-plone-org please run jobs

With this simple comment all the jobs will be started automatically.

Happy hacking!

[rpatterson]

@jenkins-plone-org please run jobs

[rpatterson]

Everything is green, @jensens. LMK if there's anything I can do to move this forward.

[jensens]

Overall LGTM. Suggested minor change would be nice to get rid of old format strings.

[rpatterson]

LMK if I should merge this myself or if there's otherwise anything I should do to get this merged, @jensens.

[Rudd-O]

Wow, this is astonishingly good work. Not only is the code clearer, it must have taken a helluva lot of work to understand the old one (in particular with the amount of context needed from back in the Zope 2 days) and get it working again. Thanks.