Discussions related to system and C std library used in the Val library

[C-BJ]

The discussion continues from here: #521

Description of the issue under discussion: In the short term, the Val library needs to use the C std library and other System libraries as interfaces. Windows and MacOS/Linux are a bit different in this respect, which means that we need to do some abstraction of our own, or use a library that is absolutely cross-platform

Although this is now just a matter of a few functions that can be easily solved, @kyouko-taiga suggests that we must first plan the relevant design

My research is limited and my qualifications are limited, so I'm likely missing some of the right solutions, so please feel free to offer your thoughts

These are several options:

1. Using Microsoft C/C++ library UCRT(In fact the glue code should not be much)
   1. Write C shims for Libc and link them to Val (similar to what the "support library" was doing)
   2. Or get started with conditional compilation, Call different functions for different systems in Val(Conditional compilation of Library/Val/LibC.val) (I prefer to use this method and I have created the prototype in my PR)
2. Use libc(gcc) or similar C standard library on Windows(The configuration process can be difficult and I have not successfully tested locally)