plumb URDF/SDF audio_source into PhysicsServerCommandProcessor, allow to play sounds on collision !

See also https://youtu.be/eppOjTfx5Jg for a first test, and this modified URDF how to add sounds:
https://github.com/bulletphysics/bullet3/blob/master/data/plane_with_collision_audio.urdf
Add the --audio flag to enable sound in pybullet/Bullet-C-API

examples/RobotSimulator/MinitaurSetup.cpp

@@ -2,6 +2,7 @@
 #include "b3RobotSimulatorClientAPI.h"
 
 #include "Bullet3Common/b3HashMap.h"
+#include "../Utils/b3HashString.h"
 
 struct MinitaurSetupInternalData
 {