Add missing include to PointCloudPackedUtils

[chapulina]

🦟 Bug fix

Summary

This manifested itself quite late when packaging downstream Garden nightlies 😢 I wish some linter would have caught this on the original PR:

• Add PointCloudPacked iterators #210

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• 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 #218 (05ed123) into ign-msgs5 (b5225fe) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           ign-msgs5     #218   +/-   ##
==========================================
  Coverage      85.27%   85.27%           
==========================================
  Files              9        9           
  Lines            903      903           
==========================================
  Hits             770      770           
  Misses           133      133           

Impacted Files	Coverage Δ
...lude/ignition/msgs/detail/PointCloudPackedUtils.hh	94.80% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b5225fe...05ed123. Read the comment docs.

[osrf-triage]

This pull request has been mentioned on Gazebo Community. There might be relevant details there:

https://community.gazebosim.org/t/new-ignition-releases-2022-03-25-fortress-edifice-citadel/1343/1