Proposal：add a flag to support custom suffixes for IDL

[Skyenought]

Why did this proposal come up？

For reference, kitex supports custom suffix names, and Hertz makes it mandatory to determine IDL type by suffix.

I propose to unify the code style for the same cloudwego subproject.

Describe alternatives you've considered

From a user experience point of view, the type is determined by the suffix by default, but the option to customize the suffix is left to the user.

For Kitex, add the default suffix determination function, but also support custom suffixes.

Hertz adds the function of custom suffixes.

为什么会出现这个提案 ？

参考 kitex 支持自定义后缀名，Hertz 为强规定通过后缀判断 IDL 类型。 我提议同属于 cloudwego 的子项目，最好统一代码风格。

描述你想要的解决方案

从用户体验的角度来看， 默认通过后缀判断类型，但是还是要留给用户去自定义后缀的选项。

即给 kitex 增加默认后缀判断功能，但同时支持自定义后缀。

Hertz 增加自定义后缀的功能。