[swift2objc] Property Parsing and Generation Refactoring

[nikeokoronkwo]

This pull request makes changes to property parsing, transformation, and generation logic for properties, which should cover the following:

• Refactor property parsing to use declarationFragments
• Change transformation to use get/set rather than functions (except specific use-cases)
• Refactor and add generation
• Create unit tests for parsing property information
• Update integration tests

[github-actions]

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// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

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pkgs/jni/lib/src/third_party/generated_bindings.dart
pkgs/objective_c/lib/src/ns_input_stream.dart

[liamappelbe]

LGTM, but the workflow hasn't run