Rewrite `span_location()` with new proc_macro's span apis

Since the proc_macro's `Span::column()` and `Span::line()` APIs are in stable rust now:
https://doc.rust-lang.org/proc_macro/struct.Span.html#method.column

We could rewrite `span_location()` in `macros/src/lexer.rs` with these new apis. The previous implementation is hacking the Debug print and with the new apis it would be much cleaner. However, it would require rust version to be at least 1.88.