Tries to fix a scenario when a user sends a malformed point cloud

[arjo129]

🦟 Bug fix

Fixes #

Summary

This PR fixes a rather odd bug. Essentially if a user were to malform a pointcloud by claiming the point cloud to contain only "x,y,z" fields but has a datasize larger than that, the condition iterX == iterX.End() && iterY == iterY.End() && iterZ == iterZ.End(); does not get met. Thus the system will keep iterating till a segfault comes along. This PR enforces better check to make sure we do not segfault.

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)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #494 (e610455) into gz-gui7 (0d754ab) will decrease coverage by 0.04%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           gz-gui7     #494      +/-   ##
===========================================
- Coverage    67.82%   67.77%   -0.05%     
===========================================
  Files           44       44              
  Lines         4826     4829       +3     
===========================================
  Hits          3273     3273              
- Misses        1553     1556       +3     

Impacted Files	Coverage Δ
src/plugins/point_cloud/PointCloud.cc	16.58% <0.00%> (-0.24%)	⬇️

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[hidmic]

codecov wants tests :)