Make tram and other vehicle sounds positional

[kfarr]

<a-mixin id="tram" gltf-model="#trammodel" sound="src: #tram-pass-mp3;positional:true;distanceModel:inverse;refDistance:5;rolloffFactor:3;volume: 1"></a-mixin>

• audio artifacts on playback using positional audio, likely due to the overly complex scene that is skipping frames in Oculus Quest headset.
• Further, those are not the perfect variable settings as the tram is in motion which results in quieter audio when it approaches and leaves (but correct while it is nearby) so more tweaking will be necessary for this specific use case.