ForeignKey _id UniqueConstraint discrepancy

[kbehlers]

Related to #9410 and #7173, so not sure if it belongs as a comment on one of those or should be a separate bug ticket.

The implementation for ModelSerializer generating UniqueConstraints gets circumvented if the UniqueConstraint involves a ForeignKey and the UniqueConstraint.fields uses the syntax without the _id suffix but the ModelSerializer.Meta.fields uses the syntax with _id suffix.

It appears to be related to https://github.com/encode/django-rest-framework/pull/7438/files#diff-c33f1f011c9f5cf3ed1357b809ebf2b4ed0b808b227c6c007291bf9b259422ecR1449, which compares field_names and unique_together_list without considering that the UniqueConstraint is allowed to include a ForeignKey that doesn't have the _id suffix.

Minimum Reproducible Example:

from django.db import models

class OtherExample(models.Model):
    pass


class Example(models.Model):
    other_example = models.ForeignKey(
        to=OtherExample,
        on_delete=models.CASCADE,
    )

    class Meta:
        constraints = [
            models.UniqueConstraint(
                fields=[
                    "id",
                    # "other_example_id",  # this questionably raises AssertionError: May not set both `read_only` and `required`
                    "other_example",  # this does not raise, but probably should raise something
                ],
                name="unique_id_and_other_example",
            )
        ]


from rest_framework import serializers


class ExampleModelSerializer(serializers.ModelSerializer):
    # other_example_id = serializers.IntegerField()  # another workaround
    class Meta:
        model = Example
        fields = [
            "id",
            "other_example_id",
        ]


from django.test import TestCase


class TestExampleModelSerializer(TestCase):
    def test_unique_constraint(self):
        ser = ExampleModelSerializer(data={"id": 1, "other_example_id": 1})
        assert ser.is_valid()