fix: fix comment for new added files.

- translate zh-CN comment into en-US.
- change some comment into Doxygen style.
- add lost Doxygen comment.
- enrich the testbench for ceil_div.
- add lost metaprogramming functions for some files in macro namespace.

src/yycc/string/op.cpp

@@ -1,5 +1,4 @@
 #include "op.hpp"
-
 #include <algorithm>
 
 namespace yycc::string::op {