Add Profiling (Lite) functionality

[bitsandfoxes]

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This is more like a brain-dump than an actionable issue for now. Feel free to chime in.

In an ideal world, we'd ship with a profiler, and have detailed and granular insights as part of the offering. But that's technically somewhat unfeasible and there the issue with performance overhead. Additionally, the profiler is part of the Editor and developers typically profile on their machine.

Instead, what we could look into are general bottlenecks.

Unity has a fixed execution order of systems. What we could do here is hook up into this life-cycle and time it. This would allow us to answer general questions like

• How much time is spent on rendering each frame?
• How much time is spent on physics?
• How much time is spent on updating the game logic (user code - all update-calls combined)

That, combined with the context that the SDK is already collecting (i.e. device/OS) would already provide valuable insights.