Implement blank_line_after_nested_stub_class preview style (#9155)

## Summary

This PR implements the `blank_line_after_nested_stub_class` preview
style in the formatter.

The logic is divided into 3 parts:
1. In between preceding and following nodes at top level and nested
suite
2. When there's a trailing comment after the class
3. When there is no following node from (1) which is the case when it's
the last or the only node in a suite

We handle (3) with `FormatLeadingAlternateBranchComments`.

## Test Plan

- Add new test cases and update existing snapshots
- Checked the `typeshed` diff

fixes: #8891

crates/ruff_python_formatter/resources/test/fixtures/ruff/stub_files/blank_line_after_nested_stub_class.options.json

@@ -0,0 +1,6 @@
+[
+  {
+    "source_type": "Stub",
+    "preview": "enabled"
+  }
+]

crates/ruff_python_formatter/resources/test/fixtures/ruff/stub_files/blank_line_after_nested_stub_class.pyi

@@ -0,0 +1,183 @@
+class Top1:
+    pass
+class Top2:
+    pass
+
+class Top:
+    class Ellipsis: ...
+    class Ellipsis: ...
+
+class Top:
+    class Ellipsis: ...
+    class Pass:
+        pass
+
+class Top:
+    class Ellipsis: ...
+    class_variable = 1
+
+class Top:
+    class TrailingComment:
+        pass
+    # comment
+    class Other:
+        pass
+
+class Top:
+    class CommentWithEllipsis: ...
+    # comment
+    class Other: ...
+
+class Top:
+    class TrailingCommentWithMultipleBlankLines:
+        pass
+
+
+    # comment
+    class Other:
+        pass
+
+class Top:
+    class Nested:
+        pass
+
+    # comment
+    class LeadingComment:
+        pass
+
+class Top:
+    @decorator
+    class Ellipsis: ...
+    class Ellipsis: ...
+
+class Top:
+    @decorator
+    class Ellipsis: ...
+    @decorator
+    class Ellipsis: ...
+
+class Top:
+    @decorator
+    class Ellipsis: ...
+    @decorator
+    class Pass:
+        pass
+
+class Top:
+    class Foo:
+        pass
+
+
+
+
+    class AfterMultipleEmptyLines:
+        pass
+
+class Top:
+    class Nested11:
+        class Nested12:
+            pass
+    class Nested21:
+        pass
+
+class Top:
+    class Nested11:
+        class Nested12:
+            pass
+        # comment
+    class Nested21:
+        pass
+
+class Top:
+    class Nested11:
+        class Nested12:
+            pass
+    # comment
+    class Nested21:
+        pass
+    # comment
+
+class Top1:
+    class Nested:
+        pass
+class Top2:
+    pass
+
+class Top1:
+    class Nested:
+        pass
+    # comment
+class Top2:
+    pass
+
+class Top1:
+    class Nested:
+        pass
+# comment
+class Top2:
+    pass
+
+if foo:
+    class Nested1:
+        pass
+    class Nested2:
+        pass
+else:
+    pass
+
+if foo:
+    class Nested1:
+        pass
+    class Nested2:
+        pass
+    # comment
+elif bar:
+    class Nested1:
+        pass
+# comment
+else:
+    pass
+
+if top1:
+    class Nested:
+        pass
+if top2:
+    pass
+
+if top1:
+    class Nested:
+        pass
+    # comment
+if top2:
+    pass
+
+if top1:
+    class Nested:
+        pass
+# comment
+if top2:
+    pass
+
+try:
+    class Try:
+        pass
+except:
+    class Except:
+        pass
+foo = 1
+
+match foo:
+    case 1:
+        class Nested:
+            pass
+    case 2:
+        class Nested:
+            pass
+    case _:
+        class Nested:
+            pass
+foo = 1
+
+class Eof:
+    class Nested:
+        pass

crates/ruff_python_formatter/resources/test/fixtures/ruff/stub_files/blank_line_after_nested_stub_class_eof.options.json

@@ -0,0 +1,6 @@
+[
+  {
+    "source_type": "Stub",
+    "preview": "enabled"
+  }
+]

crates/ruff_python_formatter/resources/test/fixtures/ruff/stub_files/blank_line_after_nested_stub_class_eof.pyi

@@ -0,0 +1,17 @@
+# A separate file to test out the behavior when there are a mix of blank lines
+# and comments at EOF just after a nested stub class.
+
+class Top:
+    class Nested1:
+        class Nested12:
+            pass
+        # comment
+    class Nested2:
+        pass
+
+
+
+# comment
+
+
+