[Feature] Allow Unknown Options from all sources

For the command line parser, there is the [`allow_unregistered()` method](https://www.boost.org/doc/libs/1_70_0/doc/html/program_options/howto.html#id-1.3.32.6.9) to not throw an exception whenever an option is not recognized.

However, this is missing from the configuration file and environment parsers.

It is possible to do work around this for both [configuration files](https://stackoverflow.com/questions/23664503/parsing-unregistered-options-for-config-files-in-boost-program-options) and [environment](https://stackoverflow.com/questions/53285248/boost-program-options-allow-undeclared-from-environment), but I am of the opinion this should be handled in similar fashion to the command line parsers!

先从命令行解析中已记录的 allow_unregistered() 行为开始，然后比较配置文件解析器和环境解析器如何处理未知选项。在决定现有解析器应如何行为之前，先查看链接的配置和环境变通方案。完成的标准是：三个来源中的未知选项都能以一致的方式处理，且没有例外。

由索引模型根据 Issue 内容生成。