Implement the iswctype and wctype functions from <wctype.h>. - Add wctype_t type definition. - Implement wctype to map property strings to classification descriptors. - Implement iswctype as a dispatcher over existing wide character classification functions. - Add corresponding entrypoints and unit tests. Refs: https://github.com/llvm/llvm-project/issues/191076 --------- Co-authored-by: Zile Xiong <xiongzile99@gmail.com>