Fix segmentation camera color id computation with new math::Color clamping behavior (ogre2)

[iche033]

🦟 Bug fix

Summary

gz-sensors caught a crash in in its segmentation camera integration test on github actions. The error msgs reveal that it related to the new color clamping behavior in gz::math::Color:

2024-08-19T23:31:54.9495719Z Color values were clamped
2024-08-19T23:31:54.9495817Z Color values were clamped
2024-08-19T23:31:54.9495909Z Color values were clamped

The new Color behavior expects the range to be within [0, 1] but we are passing it values of [0, 255].

More info on the crash: the crash was due to infinite recursion. The function tried to compute (recursively) unique color ids but each new generated color gets clamped to the same value [1, 1, 1].

To test:

Run the gz-sensors segmentation camera integration test:

./build/gz-sensors9/bin/INTEGRATION_segmentation_camera 

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)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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