feat: add various detector.

- add endian and compiler detector, and modify os detector.
- now we use CMake to add detector-used macro, instead of using some C++ features to detect them.
- change Windows environment detection according to the change of os detector.

src/yycc/encoding/windows.cpp

@@ -1,6 +1,6 @@
 #include "windows.hpp"
 
-#if YYCC_OS == YYCC_OS_WINDOWS
+#if defined(YYCC_OS_WINDOWS)
 
 #include "../string/reinterpret.hpp"
 #include <limits>