Show unused public properties and methods

It would be nice to have unused detection expanded, capable of detecting unused methods, exports, etc.

Code Example

Shape.js

class Shape {
    constructor() {
        this.color = 'red';
    }

    colorLog() {
        console.log(this.color);
    }
}

export default Shape;

Circle.js

import Shape from "./Shape";

class Circle extends Shape {
  constructor() {
    super();

    // FIXME: description should show as unused in VSCode, as it does in WebStorm.
    this.description = 'A circle shape';
  }

  // FIXME: circleLog should show as unused in VSCode, as it does in WebStorm.
  circleLog() {
    // NOTE: both VSCode and WebStorm have detected an unused variable.
    const num = 2;

    // NOTE: colorLog is being used, so no unused code errors in Shape.js file.
    super.colorLog();
  }
}

// FIXME: export should show as unused in VSCode, as it does in WebStorm.
export default Circle;

VSCode Screen

WebStorm Screen

从 Shape.js 和 Circle.js 示例开始，将所请求的未使用属性、方法和导出的诊断与 VSCode 中的当前行为进行比较。在继续之前，确定相关的 TypeScript 语言服务入口点和测试；完成的标准是报告示例中显示的未使用公共成员，同时不导致已使用成员出现回归。