Support specifying the model location in the .mat files itself

At the moment, the model corresponding to the dataset needs to be specified manually using the "Set Robot Model" menu. If that is not specified, the following error occurs:
~~~
[ERROR] ModelLoader :: loadModelFromFile : Error in parsing model from URDF.
~~~

It would be great if the model location could be encoded with a ROS or Gazebo style uri as part of dataset itself, so that the model could be directly opened if it is available, or a clear error printed if a given model is not available in the system/environment. Probably this would require also modifications on the blf's robot logger side.

Start by tracing the Set Robot Model menu and the ModelLoader URDF parsing path named in the report. Review how the .mat dataset is produced, including the blf robot logger side, and compare the proposed ROS/Gazebo-style URI behavior. Done means an available model can be opened from dataset metadata and a missing model produces a clear error.

Written by the indexing model from the issue text.