[Feature]: Create Test-Route/-Scenario with Dev-Launch incl. vehicles + 1st person spectator

[MaxJa4]

Description

We currently test our code with either the evaluation route or by driving in the dev-launch environment.
Inside the eval-route, we cannot alter or specifically test anything.
In dev-launch, there are currently no vehicles and the spectator camera is floating off the map.
Additionally, there is a memory leak when using dev-launch.

The goal is to enhance and extend dev-launch to have a 1st person spectator, spawned vehicles and a configurable environment for testing our code.

Definition of Done

• Dev launch spawns vehicles
• Spectator is spawned at the ego vehicle instead of outside the map
• Scenarios (start position, vehicle count, ...) can be configured