formatter: support formatting bindings, for example in a let (#2883)

common/util/string_util.cpp

@@ -46,8 +46,6 @@ std::string ltrim(const std::string& s) {
   return (start == std::string::npos) ? "" : s.substr(start);
 }
 
-// TODO - used a lot in formatting, and its slow because i bet it iterates from the start and not
-// the end
 std::string rtrim(const std::string& s) {
   size_t end = s.find_last_not_of(WHITESPACE);
   return (end == std::string::npos) ? "" : s.substr(0, end + 1);