Added invalid point checking to RGBD and Depth Camera plugins to set is_dense flag accordingly (backport #575)

[mergify]

🦟 Bug fix

Fixes #574

Summary

Fix similar to #180. Added gz::math::isnan and std::isinf checks to depth/coordinates in all FillMsg methods in PointUtil.cc
, which RGBD Camera and Depth Camera depend on.

Reproducibility steps described in #574.
New output should look the same, except for the is_dense flag, which should be set to false.

(maybe another test/world should be done where the point cloud only contains valid points, to check if is_dense is correctly set to true)

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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This is an automatic backport of pull request #575 done by Mergify.