Add a system check for a model property name that clashes with a foreign key id accessor

[Michael]

Summary

Given a model with a foreign key field "foo", it would be helpful if Django warned users when they include a property in the model named "foo_id" in the same model.

Steps To Reproduce

• Implement a relationship that looks like Exhibit A
• Create an instance of Bar using .create or FactoryBoy.
• Observe the following stack trace that occurs in Exhibit B

Expected Results
As a Django user, I expect the framework to warn me with a helpful error if I name a property method that doesn't play nice with Django's ORM.

// Exhibit A

class Foo(models.Model):
  pass

class Bar(models.Model):
  foo = models.ForeignKey(Foo)

  @property
  def foo_id(self):
    return self.foo.id

// Exhibit B
Traceback (most recent call last):
  File "./manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/__init__.py", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python3.6/dist-packages/django/core/management/commands/shell.py", line 101, in handle
    exec(sys.stdin.read())
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.6/dist-packages/factory/base.py", line 46, in __call__
    return cls.create(**kwargs)
  File "/usr/local/lib/python3.6/dist-packages/factory/base.py", line 568, in create
    return cls._generate(enums.CREATE_STRATEGY, kwargs)
  File "/usr/local/lib/python3.6/dist-packages/factory/base.py", line 505, in _generate
    return step.build()
  File "/usr/local/lib/python3.6/dist-packages/factory/builder.py", line 279, in build
    kwargs=kwargs,
  File "/usr/local/lib/python3.6/dist-packages/factory/base.py", line 314, in instantiate
    return self.factory._create(model, *args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/factory/django.py", line 165, in _create
    return manager.create(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/query.py", line 392, in create
    obj = self.model(**kwargs)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/base.py", line 555, in __init__
    _setattr(self, field.name, rel_obj)
  File "/usr/local/lib/python3.6/dist-packages/django/db/models/fields/related_descriptors.py", line 253, in __set__
    setattr(instance, lh_field.attname, getattr(value, rh_field.attname))
AttributeError: can't set attribute