HarmonyOS ResourceColor 转16进制 string

通过resourceManager中的getColorSync获得对应颜色的十进制数，再转16进制参考demo：

let resource: resourceManager.Resource = {
  bundleName: "com.example.helloworld",
  moduleName: "entry",
  id: $r('app.color.start_window_background').id
};
let colorNumber = this.context.resourceManager.getColorSync(resource);
let colorString = colorNumber.toString(16)
console.log(colorString);

参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-resource-manager-V5#getcolorsync10