Allow Extract Constant in expression-bodied arrow functions

const f = () => 1 + [#|(2 + 3)|] + 4;

Expected:

const f = () => {
    const newLocal = (2 + 3);
    return 1 + newLocal + 4;
};

We can detect this scenario, but ChangeTracker doesn't support overlapping transformations (i.e. substituting newLocal into the expression and then putting the result into a return statement).

首先定位 Extract Constant 重构的入口点，以及 ChangeTracker 对表达式体箭头函数的处理逻辑。复现 issue 中的 TypeScript 示例，并跟踪常量替换和 return 转换是如何表示的。完成的标准是：所示表达式被转换为具有局部常量和 return 语句的块体箭头函数。