[`flake8-django`] Skip duplicate violations in `DJ012` (#5469)

## Summary

This PR reduces the noise from `DJ012` by emitting a single violation
when you have multiple consecutive violations of the same "type".

For example, given:

```py
class MultipleConsecutiveFields(models.Model):
    """Model that contains multiple out-of-order field definitions in a row."""


    class Meta:
        verbose_name = "test"

    first_name = models.CharField(max_length=32)
    last_name = models.CharField(max_length=32)
```

It's convenient to only error on `first_name`, and not `last_name`,
since we're really flagging that the _section_ is out-of-order.

Closes #5465.

crates/ruff/resources/test/fixtures/flake8_django/DJ012.py

@@ -111,3 +111,19 @@ class PerfectlyFine(models.Model):
     @property
     def random_property(self):
         return "%s" % self
+
+
+class MultipleConsecutiveFields(models.Model):
+    """Model that contains multiple out-of-order field definitions in a row."""
+
+
+    class Meta:
+        verbose_name = "test"
+
+    first_name = models.CharField(max_length=32)
+    last_name = models.CharField(max_length=32)
+
+    def get_absolute_url(self):
+        pass
+
+    middle_name = models.CharField(max_length=32)

crates/ruff/src/rules/flake8_django/rules/unordered_body_content_in_model.rs

@@ -63,20 +63,23 @@ use super::helpers;
 /// [Django Style Guide]: https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/coding-style/#model-style
 #[violation]
 pub struct DjangoUnorderedBodyContentInModel {
-    elem_type: ContentType,
+    element_type: ContentType,
-    before: ContentType,
+    prev_element_type: ContentType,
 }
 
 impl Violation for DjangoUnorderedBodyContentInModel {
     #[derive_message_formats]
     fn message(&self) -> String {
-        let DjangoUnorderedBodyContentInModel { elem_type, before } = self;
+        let DjangoUnorderedBodyContentInModel {
-        format!("Order of model's inner classes, methods, and fields does not follow the Django Style Guide: {elem_type} should come before {before}")
+            element_type,
+            prev_element_type,
+        } = self;
+        format!("Order of model's inner classes, methods, and fields does not follow the Django Style Guide: {element_type} should come before {prev_element_type}")
     }
 }
 
 #[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq)]
-pub(crate) enum ContentType {
+enum ContentType {
     FieldDeclaration,
     ManagerDeclaration,
     MetaClass,
@@ -149,24 +152,38 @@ pub(crate) fn unordered_body_content_in_model(
     {
         return;
     }
-    let mut elements_type_found = Vec::new();
+
+    // Track all the element types we've seen so far.
+    let mut element_types = Vec::new();
+    let mut prev_element_type = None;
     for element in body.iter() {
-        let Some(current_element_type) = get_element_type(element, checker.semantic()) else {
+        let Some(element_type) = get_element_type(element, checker.semantic()) else {
             continue;
         };
-        let Some(&element_type) = elements_type_found
+
+        // Skip consecutive elements of the same type. It's less noisy to only report
+        // violations at type boundaries (e.g., avoid raising a violation for _every_
+        // field declaration that's out of order).
+        if prev_element_type == Some(element_type) {
+            continue;
+        }
+
+        prev_element_type = Some(element_type);
+
+        if let Some(&prev_element_type) = element_types
             .iter()
-            .find(|&&element_type| element_type > current_element_type) else {
+            .find(|&&prev_element_type| prev_element_type > element_type)
-                elements_type_found.push(current_element_type);
+        {
-                continue;
-        };
             let diagnostic = Diagnostic::new(
                 DjangoUnorderedBodyContentInModel {
-                elem_type: current_element_type,
+                    element_type,
-                before: element_type,
+                    prev_element_type,
                 },
                 element.range(),
             );
             checker.diagnostics.push(diagnostic);
+        } else {
+            element_types.push(element_type);
+        }
     }
 }

crates/ruff/src/rules/flake8_django/snapshots/ruff__rules__flake8_django__tests__DJ012_DJ012.py.snap

@@ -37,4 +37,21 @@ DJ012.py:69:5: DJ012 Order of model's inner classes, methods, and fields does no
    | |____________^ DJ012
    |
 
+DJ012.py:123:5: DJ012 Order of model's inner classes, methods, and fields does not follow the Django Style Guide: field declaration should come before `Meta` class
+    |
+121 |         verbose_name = "test"
+122 | 
+123 |     first_name = models.CharField(max_length=32)
+    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ DJ012
+124 |     last_name = models.CharField(max_length=32)
+    |
+
+DJ012.py:129:5: DJ012 Order of model's inner classes, methods, and fields does not follow the Django Style Guide: field declaration should come before `Meta` class
+    |
+127 |         pass
+128 | 
+129 |     middle_name = models.CharField(max_length=32)
+    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ DJ012
+    |
+