Check that CheckConstraint.check and UniqueConstraint.condition don't span joins.

[Simon Charette]

Similar to #31410 but for check and condition.

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Not everyone is familiar with the fact database level constraint cannot span across tables and might be tempted to do

class Person(models.Model):
    age = models.PositiveSmallIntegerField()
    parent = models.ForeignKey(self)

    class Meta:
        constraints = {
            CheckConstraint(
                name='age_lt_parent', check=Q(age__lt=parent__age)
            ),
        }

Which we'll happily create migrations for but we'll then crash because we prevent JOINs when resolving check.