[Ogre2] Fix invalid anti-aliasing level warning

[srmainwaring]

🦟 Bug fix

Fixes issue discussed in #463 (comment)

Summary

This PR fixes a bug where the invalid anti-aliasing level warning in Ogre2RenderTarget::TargetFSAA() was not being output and the FSAA level was not being set to a default value of 0. This can cause the scene to fail to render.

The code will now output a warning, provide a list of valid options and set the anti-aliasing level to 0.

The code can be tested by changing the camera anti-aliasing level in the simple_demo example:

Modify:

https://github.com/ignitionrobotics/ign-rendering/blob/1c77a8ac05cce3ed5a5b99e56030db833ad67b0a/examples/simple_demo/Main.cc#L179

to

// create camera
camera->SetAntiAliasing(3);

The console output is:

[Wrn] [Ogre2RenderTarget.cc:573] Anti-aliasing level of '3' is not supported; valid FSAA levels are: [ 1 2 4 8 ]. Setting to 0

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

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[codecov]

Codecov Report

Merging #470 (b6fe335) into ign-rendering6 (1c77a8a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head b6fe335 differs from pull request most recent head daa62d8. Consider uploading reports for the commit daa62d8 to get more accurate results

@@                Coverage Diff                 @@
##           ign-rendering6     #470      +/-   ##
==================================================
+ Coverage           53.50%   53.51%   +0.01%     
==================================================
  Files                 192      192              
  Lines               19562    19569       +7     
==================================================
+ Hits                10466    10473       +7     
  Misses               9096     9096              

Impacted Files	Coverage Δ
ogre2/src/Ogre2RenderTarget.cc	86.05% <100.00%> (-0.01%)	⬇️
...e/ignition/rendering/base/BaseGaussianNoisePass.hh	100.00% <0.00%> (+3.33%)	⬆️

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[iche033]

looks good to me

[iche033]

retriggered a couple of CI builds that failed for unrelated reason. Merging this once CI is green