Add todo! & unimplemented! to format macros list

For some reason, the `todo!` and `unimplemented!` macros were not included in the list of format-supporting macros list. Since they seem to behave exactly the same as all others like `write!` and `assert!`, adding them now.

Author: nyurik

clippy_utils/src/macros.rs

@@ -30,6 +30,8 @@ const FORMAT_MACRO_DIAG_ITEMS: &[Symbol] = &[
     sym::print_macro,
     sym::println_macro,
     sym::std_panic_macro,
+    sym::todo_macro,
+    sym::unimplemented_macro,
     sym::write_macro,
     sym::writeln_macro,
 ];