Use ignition::gazebo:: in class instantiation

[scpeters]

🦟 Bug fix

Fixes macOS build.

Summary

The macOS build has been broken since #1646:

• https://build.osrfoundation.org/view/ign-citadel/job/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/282/

In other packages, I have avoided using the gz::sim namespace when implementing classes, so doing it here seems to fix the macOS build. The ABI build is broken too, but that needs a different fix.

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 #1967 (d3484b0) into ign-gazebo3 (875de1b) will increase coverage by 0.07%.
The diff coverage is n/a.

❗ Current head d3484b0 differs from pull request most recent head aa05e3d. Consider uploading reports for the commit aa05e3d to get more accurate results

@@               Coverage Diff               @@
##           ign-gazebo3    #1967      +/-   ##
===============================================
+ Coverage        77.96%   78.04%   +0.07%     
===============================================
  Files              255      255              
  Lines            15080    15080              
===============================================
+ Hits             11757    11769      +12     
+ Misses            3323     3311      -12     

Impacted Files	Coverage Δ
src/EntityComponentManager.cc	89.09% <ø> (ø)
src/Link.cc	93.54% <ø> (ø)
src/Model.cc	95.83% <ø> (ø)
src/SdfEntityCreator.cc	90.44% <ø> (ø)
src/ServerConfig.cc	90.28% <ø> (ø)
src/SystemLoader.cc	81.96% <ø> (ø)
src/TestFixture.cc	100.00% <ø> (ø)
src/World.cc	96.87% <ø> (ø)
...rc/systems/ackermann_steering/AckermannSteering.cc	85.54% <ø> (ø)
src/systems/air_pressure/AirPressure.cc	73.17% <ø> (ø)
... and 30 more

... and 1 file with indirect coverage changes

[mjcarroll]

macOS build doesn't seem to like that.

[scpeters]

macOS build doesn't seem to like that.

it's because I removed broken bottles in osrf/homebrew-simulation#2242, which maybe I didn't have to do as a separate step? At any rate, rebuilding the gz-common3 bottle in osrf/homebrew-simulation#2245 which should fix it

[scpeters]

macOS build doesn't seem to like that.

it's because I removed broken bottles in osrf/homebrew-simulation#2242, which maybe I didn't have to do as a separate step? At any rate, rebuilding the gz-common3 bottle in osrf/homebrew-simulation#2245 which should fix it

homebrew build is now unstable, I believe because it ran on macos-monterey and there are some failing tests due to gazebosim/gz-physics#442

[scpeters]

I believe the ABI checker is failing due to #1971

[scpeters]

CI is 🟢 ! Hooray!