Update AddModelFromFile -> AddModels

[yunho-c]

Hi Vince, thank you for sharing this great project!

Running examples.simulation_demo results in errors saying AddModelFromFile is undefined.

Traceback (most recent call last):
  ...
  File ".../kinova_drake/kinova_station/simulation_station.py", line 243, in SetupSinglePegScenario
    self.AddArmWithHandeGripper(arm_damping=arm_damping)
  File ".../kinova_drake/kinova_station/simulation_station.py", line 400, in AddArmWithHandeGripper
    self.AddArm(include_damping=arm_damping)
  File ".../kinova_drake/kinova_station/simulation_station.py", line 294, in AddArm
    self.arm = Parser(plant=self.plant).AddModelFromFile(arm_urdf, "arm")
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'pydrake.multibody.parsing.Parser' object has no attribute 'AddModelFromFile'. Did you mean: 'AddModelsFromUrl'?

I believe this is because of changes in pydrake's API regarding the URDF/SDF file import.

I found a simple workaround and will submit a PR, but I am not sure if it addresses the problem completely/properly (since it is not possible to assign names like "arm" and "gripper" with AddModels method).