Add NeverDestroyed utility class

[mjcarroll]

🎉 New feature

Summary

Useful for function-local static variables that are not trivially destructable. This can be used to clean up "possible leak" warnings from memory-checking tools.

Originally imported from drake codebase (BSD 3-clause). It has been updated for consistency with ignition codebase.

Added in support of gazebosim/gz-math#269 at the suggestion of @jwnimmer-tri (gazebosim/gz-math#269 (comment))

Test it

Unit tests have been imported as well

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

[mjcarroll]

@jwnimmer-tri based on your comment on the ign-math issue above, we have decided to move forward with this option for classes such as math::Material.

Would it be possible for you to sign off on relicensing this to Apache 2.0? While BSD is compatible, for the ease of packaging, it helps to have as few different licenses as possible. I have deferred adding any sort of license/copyright header until I get confirmation from you.

[jwnimmer-tri]

Yes, given the git history of the header and test code, TRI (me) are the sole author. TRI (and me) grant you license under Apache-2.0 terms to contribute it here.

[codecov-commenter]

Codecov Report

Merging #31 (ce7879f) into ign-utils1 (07cb45a) will increase coverage by 0.50%.
The diff coverage is 100.00%.

@@              Coverage Diff               @@
##           ign-utils1      #31      +/-   ##
==============================================
+ Coverage       94.36%   94.87%   +0.50%     
==============================================
  Files               4        5       +1     
  Lines              71       78       +7     
==============================================
+ Hits               67       74       +7     
  Misses              4        4              

Impacted Files	Coverage Δ
include/ignition/utils/NeverDestroyed.hh	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 07cb45a...ce7879f. Read the comment docs.

[osrf-triage]

This pull request has been mentioned on Gazebo Community. There might be relevant details there:

https://community.gazebosim.org/t/new-ignition-releases-2022-03-01-citadel-edifice-fortress/1313/1