Fixed bag_to_pcd processing of static transforms

[peci1]

bag_to_pcd usage of TF interface was obsolete, so it needed a ROS master running and filled TF buffer by publishing transforms via a tf::TransformPublisher. More importantly, it did not correctly handle static TFs, which resulted in inability to resolve static frames.

This PR rewrites the code to use tf2_ros::Buffer which does not require a running ROS master and it also adds correct handling of static frames (as long as they are found on topics ending with _static).

I only did not understand why rosbag info reports for my bags that /tf topic is of type tf2_msgs/TFMessage, while the code branch taken is the one for tf::tfMessage. Maybe it's some kind of automatic conversion from TF1 to TF2 that takes place here.