Extend TrafficDefinition to pedestrians

Currently, traffic actions are only defined for Vehicles. However, there are use cases, especially in urban areas, where it would be desirable to also model stochastic behavior of pedestrians, analogous to the vehicles.

This proposal is overlapping (at least partially) with https://code.asam.net/simulation/standard/openscenario/-/issues/70

I therefore propose to modify the TrafficDefinition class (https://releases.asam.net/OpenSCENARIO/1.0.0/Model-Documentation/content/TrafficDefinition.html) such that the "vehicleCategoryDistribution" is replaced with a "trafficCategory", which then can contain either a vehicleCategoryDistribution or a pedestrianCategoryDistribution.

The pedestrianCategoryDistribution would be analogous to the vehicleCategoryDistribution.

*Suggested UML model changes

Class TrafficDefinition

replace vehicleCategoryDistribution with trafficCategory

name	type	cardinality	Applied stereotypes	Annotations
trafficCategory	TrafficCategory	1..1		Specification of the type of traffic participants

Class TrafficCategory

name	type	cardinality	Applied stereotypes	Annotations
vehicleCategoryDistribution	VehicleCategoryDistribution	1..1	xor	Distribution of vehicle categories within the traffic.
pedestrianCategoryDistribution	PedestrianCategoryDistribution	1..1	xor	Distribution of pedestrian categories within this traffic.

Class PedestrianCategoryDistribution

name	type	cardinality	Applied stereotypes	Annotations
pedestrianCategoryDistributionEntries	PedstrianCategoryDistributionEntry	1..*	XSDunwrapped	List of elements that pair pedestrian categories and their weight within the distribution.

Class PedestrianCategoryDistributionEntry

name	type	cardinality	Applied stereotypes	Annotations
category	PedestrianCategory	1..1	XSDattribute	The category of the pedestrians that appear in traffic.
weight	double	1..1	XSDattribute	The weight of a pedestrian category within a traffic distribution. Range: [0..inf[.