Describe usecase: Benchmarking and integration: OSI-GPU-radar

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Add content to ./doc/usecases/benchmark_integration_gpu_radar.adoc.

• Add a description of the use case. Why would you want to do this? What options do you have? What are the most important considerations?
• Add prerequistes of this use case. What needs to be done before you can start this use case.
• Add relevant messages including a short description of how they are relevant to this use case.
• Add one or two examples.