QuerySet.in_bulk fixes.

- Made id_list of type Sequence[Any], rather than Any, according to mkurnikov's review.
- Removed **kwargs.
- Made returned Dict keys of type Any rather than int or str as it depends on the provided field's type.
- Added test with examples from Django docs.

test-data/typecheck/queryset.test

@@ -0,0 +1,10 @@
+[CASE test_queryset]
+from django.db import models
+
+class Blog(models.Model):
+    slug = models.CharField(max_length=100)
+reveal_type(Blog.objects.in_bulk([1])) # E: Revealed type is 'builtins.dict[Any, main.Blog*]'
+reveal_type(Blog.objects.in_bulk()) # E: Revealed type is 'builtins.dict[Any, main.Blog*]'
+reveal_type(Blog.objects.in_bulk(['beatles_blog'], field_name='slug')) # E: Revealed type is 'builtins.dict[Any, main.Blog*]'
+
+[out]