Only build mesh integration tests if graphics libraries are built

[mjcarroll]

🦟 Bug fix

Fixes #522

Summary

This removes mesh.cc if the graphics component is not built either by being disabled by the user or from missing dependencies.

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 #523 (614a165) into gz-common5 (6a0f9d7) will not change coverage.
The diff coverage is n/a.

❗ Current head 614a165 differs from pull request most recent head ab262e5. Consider uploading reports for the commit ab262e5 to get more accurate results

@@             Coverage Diff             @@
##           gz-common5     #523   +/-   ##
===========================================
  Coverage       83.65%   83.65%           
===========================================
  Files              90       90           
  Lines           10249    10249           
===========================================
  Hits             8574     8574           
  Misses           1675     1675           

[Ryanf55]

LGTM, it works.