message: Do not change map from mission_impl
diff: #pragma once
  #include <json/json.h>
  -#include <unordered_map>
  +#include <map>
  #include <memory>
  #include <mutex>
  @@ -110,7 +110,7 @@ private:
  mutable std::recursive_mutex mutex{};
  int last_current_mavlink_mission_item{-1};
  int last_reached_mavlink_mission_item{-1};
  - std::unordered_map<int, int> mavlink_mission_item_to_mission_item_indices{};
  + std::map<int, int> mavlink_mission_item_to_mission_item_indices{};
  int num_mission_items_to_download{-1};
  int next_mission_item_to_download{-1};
  int last_mission_item_to_upload{-1};
  