ROS message conversion needs access to /tf and /tf_static

[twojtasz]

ROS messages include a frame_id, which is a named transform.

Currently the @xviz/ros package provides a map of names to transforms when constructing metadata but it is needed for dynamic transforms at convertMessage() time in the Converters.

The plan is to add a transforms parameter to the convertMessage() method and ensure that the data from those streams is provided to converters.

It may be preferred to provide the raw transform as well as methods to get a Pose class which allows for the transforms to be applied to data easier.