[ign-rendering3] Workflow updates

[chapulina]

• Add labeler workflow
• Add triage workflow
• Add Ubuntu CI workflow with Codecov upload
• Update codecov badge
• Port CODEOWNERS

[iche033]

should I expect to see a codecov.io comment in the PR?

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (ign-rendering3@44e8f39). Click here to learn what that means.
The diff coverage is n/a.

@@               Coverage Diff                @@
##             ign-rendering3     #80   +/-   ##
================================================
  Coverage                  ?   7.81%           
================================================
  Files                     ?      25           
  Lines                     ?    1689           
  Branches                  ?       0           
================================================
  Hits                      ?     132           
  Misses                    ?    1557           
  Partials                  ?       0           

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[chapulina]

should I expect to see a codecov.io comment in the PR?

Yup, fixed!

[chapulina]

The test coverage is really low for all branches. I'm not sure why and didn't look too close at the logs, some guesses:

• Optix not being installed means we lose about 1/3 of coverage
• GitHub actions doesn't support GPU tests

At least some tests are running though, so I think we can close #44.

[iche033]

I think it's also running for ogre 1.x only and not ogre 2.1 so another 1/3 of coverage lost

[chapulina]

Oh that reminds me of this issue, which I think I put on ign-gazebo by mistake, when I meant to put it on ign-rendering gazebosim/gz-sim#14