Verify and document capability to ROS 2 simulation non-realtime.

Is your feature request related to a problem? Please describe. A lot of other simulation products support non-realtime simulation. That is useful in scenarios like:

complex, challenging mechanical systems (e.g. humanoid robots),
hardware in the loop simulation,
potentially using non-realtime, non-game physics engines in O3DE for simulation
using prerecorded data (e.g. from real system, or other simulation software)

Describe the solution you'd like Detailed documentation both in gem source code and in o3de.org on:

Current support for non-realtime simulation,
Current support for external time source (provided by /clock to the o3de simulation from the other engine (e.g. Gazebo) or ROS 2 bag file.
Explain known technological limitations (PhysX, Atom integration, ROS 2 cameras, RGL lasers)
Test the whole ROS 2 Gem functionality (both by running simulation and code review) to find bugs like #709.
Document #707.

A good start is to set PhysX to work slower than real-time: As you can see in the video, the clock respects correctly the slower time, when StableClock is used: https://github.com/o3de/o3de-extras/assets/3209244/4ee3f59f-314e-4ef5-8838-c41152b0a9e0

Describe alternatives you've considered

Additional context No more context.

o3de / o3de-extras

Verify and document capability to ROS 2 simulation non-realtime. #710