[struct_pack] add config DISABLE_ALL_META_INFO

[poor-circle]

Why

now we can disable all meta info include hash code to reduce binary size

What is changing

Example

struct rect {
  var_int a, b, c, d;
  bool operator==(const rect& o) const {
    return a == o.a && b == o.b && c == o.c && d == o.d;
  }
};

//clang-format off
void serialize_config() {
  // serialize with config
  rect r{1, -1, 0, 5};
  auto buffer =
      struct_pack::serialize<struct_pack::DISABLE_ALL_META_INFO>(
          r);
  // only need 4 bytes
  assert(buffer.size() == 4);
  // deserialize with config
  auto result =
      struct_pack::deserialize<struct_pack::DISABLE_ALL_META_INFO, rect>(
          buffer);
  assert(result.value() == r);
}

// or, you can also use ADL helper function to config it. this function should
// in the same namespace of type
inline constexpr struct_pack::sp_config set_sp_config(rect*) {
  return struct_pack::DISABLE_ALL_META_INFO;
}

void serialize_config_by_ADL() {
  // serialize with config
  rect r{1, -1, 0, 5};
  auto buffer = struct_pack::serialize(r);
  // only need 4 bytes
  assert(buffer.size() == 4);
  // deserialize with config
  auto result = struct_pack::deserialize<rect>(buffer);
  assert(result.value() == r);
}