Generate expert trajectories

[MarcelBruckner]

I want to move the expert trajectory generation near the GAIL agent because:

1. The GAIL agent is the only agent to use expert trajectories
2. Using bark to convert and then use the expert trajectories in bark-ml is unnecessary complex
3. We don't need to provide the .pkl file for the expert trajectories, but can just run the generate script near the GAIL agent.
4. Everything we do is in bark-ml, so why go to bark to extract.

[MarcelBruckner]

I converted the expert_trajectory notebook from bark and made it into a runnable script. I fixed some errors and extended the functionality. We can now:

1. Generate all expert trajectories for all found track files and all map files. The script runs for all found .csv and .xodr files
2. Converts german and chinese scene
3. Multithreaded simulate and convert all track files simultaneously
4. Run it from command line with one single bazel command
5. Set input and output paths from command line

[MarcelBruckner]

Run with:

bazel run //bark_ml/library_wrappers/lib_tf2rl:generate_expert_trajectories -- --interaction_dataset_path=<path-to-dataset-clone> --expert_trajectories_path=<output-folder>

This generates a ton of

E0611 20:53:27.652910 645133 observed_world.cpp:70] No lane corridor found.
I0611 20:53:27.669625 645133 behavior_static_trajectory.cpp:126] Agent 64: Behavior status has expired!

errors, but they are in bark so non of our business.