[jnigen] Support Kotlin operators

[HosseinYousefi]

Generate +, -, *, /, %, [], []= operators in Dart. Some of Dart operators don't exist in Kotlin and vice-versa. These are the group of operators that make sense. Also we only generate them if they fit the Dart model (For example, [] can take multiple parameters in Kotlin, while in Dart it can only get 1). If there are multiple overloads, only generate the first matching one as an operator.

We still generate the original method, this is consistent with Kotlin, as a.add(b) and a + b are equivalent.

[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

[coveralls]

coverage: 87.388% (+0.03%) from 87.356%
when pulling 8b74bf4 on kotlin-operators
into b053b7b on main.