Added the mixins LoginRequiredMixin, PermissionRequiredMixin and
UserPassesTestMixin to contrib.auth as counterparts to the respective
view decorators.

The authentication mixins UserPassesTestMixin, LoginRequiredMixin and
PermissionRequiredMixin have been inspired by django-braces
<https://github.com/brack3t/django-braces/>

Thanks Raphael Michel for the initial patch, tests and docs on the PR
and Ana Balica, Kenneth Love, Marc Tamlyn, and Tim Graham for the
review.

Regression introduced in 9aac99e9

Fixed "PendingDeprecationWarning: generator 'LazyStream.read.<locals>.parts'
raised StopIteration" per PEP 0479.

Thanks Tim Graham for the review.

The idea behind this change is, that AlterUniqueTogether,
AlterIndexTogether and AlterOrderWithRespectTo can always be moved after
an Add/Alter/Rename/RemoveField operation if they don't refer to the
respective field and are not empty sets / None.

Combined with the optimizations of duplicate AlterUniqueTogether,
AlterIndexTogether, and AlterOrderWithRespectTo operations from
128caa1e, these operations are optimized
in a later round of the optimizer.

Thanks Tim Graham for the review.

This resolves a problem on databases besides PostgreSQL when using
prefetch_related with a source model that uses a UUID primary key.

Email field isn't required.

Thanks Andrew Godwin and Simon Charette for the review.

Thanks Andrew Godwin for the review.

Thanks Andrew Godwin for the review.

Thanks Andrew Godwin for the review.

This adds a test for 511a53b3

Appeared in Opera with ModelAdmin.actions=None.

Thanks Tim Graham for the patch

Fixed #12685 - Ensure that deserialised model instances honor the same arguments as normal models.