Optimization: skip applying noise and distortion to lidars and camera sensors if parameters are 0s

[iche033]

🦟 Bug fix

Summary

When Gaussian noise params and distortion coefficients are 0s, there shouldn't be any change to the sensor output. So skip doing extra computations in this case.

One instance where this usually happens is when a user saves the world to file in gz-sim, all sdf elements are written out with their default values. So when you load the saved world sdf file back in, you now have noise / distortion sdf elements present but with values of 0s.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
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• All tests passed (See test coverage)
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