Fixed #29799 -- Allowed registering lookups per field instances.

Thanks Simon Charette and Mariusz Felisiak for reviews and mentoring
this Google Summer of Code 2022 project.

tests/custom_lookups/models.py

@@ -3,6 +3,7 @@ from django.db import models
 
 class Author(models.Model):
     name = models.CharField(max_length=20)
+    alias = models.CharField(max_length=20)
     age = models.IntegerField(null=True)
     birthdate = models.DateField(null=True)
     average_rating = models.FloatField(null=True)