[leancode_lint] Handle Dart 3.13 primary constructors

[PiotrRogulski]

Makes the custom lints handle Dart 3.13's primary constructors, with new test cases for every affected rule.

Lint fixes

• missing_equatable_props: fields declared by a primary constructor's declaring parameters (class MyState(final int a) with Equatable) are now required in props, and a superclass declaring its fields in a primary constructor now triggers the super.props requirement (such fields report isOriginDeclaringFormalParameter, not isOriginDeclaration). The quick-fix handles both as well.
• constructor_parameters_and_fields_should_have_the_same_order: header-declared fields now participate in the field order (preceding body fields) when checking the class's other constructors. This also fixes a false positive where a factory's parameters matched the true field order but the lint only saw body fields.
• avoid_build_context_in_blocs: BuildContext parameters in a Bloc/Cubit's primary constructor header (plain and field-declaring) are now reported.
• prefer_abstract_final_class: a private class MyConstants._() primary constructor with no parameters and no this body is now recognized as an instantiation guard (including class const), and the fix removes it from the class header.
• convert_positional_to_named_formal assist: now preserves the parameter's own declaration instead of synthesizing required this.<name>, which corrupted a primary constructor's declaring parameters (final int x) and super.x parameters.

Notes

• Naming lints (add_cubit_suffix_for_cubits, bloc_related_class_naming, bloc_subclasses_naming, prefix_widgets_returning_slivers) already use namePart.typeName and needed no changes; a primary-constructor regression test was added for add_cubit_suffix_for_cubits.
• Non-declaring header parameters (int x without final/var) are correctly not treated as fields.
• All analyzer APIs used exist at the constraint floor (analyzer 13.0.0), so no constraint bump is needed.
• Tests were verified to fail without the lint fixes (11 failures across the four rules on the old implementations).

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https://claude.ai/code/session_01KiMgutpA35YKFfcHdXDt6E

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