Add code coverage ignore file

[AzulRadio]

Signed-off-by: youhy haoyuan2019@outlook.com

New feature

Part of gz-sim#1575

Alternative for #684

Summary

Add coverage.ignore.in to ignore vendor code in code coverage report. See gz-cmake#279 for detail.

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• 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 #689 (feb76f4) into ign-rendering3 (0d45f75) will increase coverage by 21.97%.
The diff coverage is n/a.

❗ Current head feb76f4 differs from pull request most recent head a947600. Consider uploading reports for the commit a947600 to get more accurate results

@@                 Coverage Diff                 @@
##           ign-rendering3     #689       +/-   ##
===================================================
+ Coverage           53.38%   75.36%   +21.97%     
===================================================
  Files                 131       98       -33     
  Lines               12021     7793     -4228     
===================================================
- Hits                 6418     5873      -545     
+ Misses               5603     1920     -3683     

Impacted Files	Coverage Δ
...e/ignition/rendering/base/BaseGaussianNoisePass.hh	96.66% <0.00%> (-3.34%)	⬇️
ogre/src/OgreDynamicRenderable.cc
ogre/src/OgreRenderTargetMaterial.cc
ogre/src/OgreConversions.cc
ogre/src/OgreRayQuery.cc
ogre/src/OgreMaterialSwitcher.cc
ogre/src/OgreDynamicLines.cc
ogre/src/OgreVisual.cc
ogre/src/OgreGeometry.cc
ogre/src/OgreGaussianNoisePass.cc
... and 24 more

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[chapulina]

increase coverage by 21.97%. 🚀

For future reference, we're excluding ogre for now, but as a supported engine we should be re-enabling it once #683 is resolved.