Add environment map tutorial

[iche033]

🎉 New feature

Summary

Add a new tutorial to show how to set an environment map to a mesh and also how to create a the environment map / cube map texture in gimp

Test it

Build ign-rendering and the open the doxygen index page: build/ignition-rendering5/doxygen/html/index.html

Go to Tutorials and you should see the new Environment map tutorial entry.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• 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

Note to maintainers: Remember to use Squash-Merge

[codecov]

Codecov Report

Merging #295 (939fd4d) into main (8c21e50) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #295   +/-   ##
=======================================
  Coverage   57.54%   57.54%           
=======================================
  Files         159      159           
  Lines       15590    15590           
=======================================
  Hits         8971     8971           
  Misses       6619     6619           

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