Fix a memory leak in axom::Array copy constructor

[publixsubfan]

Summary

• Fixes leak in axom::Array copy constructor, along the lines of the fix in commit ae8e8c7
• Add unit test for leaky copy/move constructors and assignment operators

[publixsubfan]

@kennyweiss -- I replaced the regression test you added in #1286 with a unit test that I think should capture all the leaky cases you were seeing. Let me know if you'd rather keep the regression test as well.

[kennyweiss]

Thanks @publixsubfan -- it looks like it covers similar/more ground, so I'm ok w/ removing the old regression case.

Did you check the bugfix against lsan and/or valgrind or a similar tool?

[rhornung67]

Thanks @publixsubfan

[gunney1]

Thank you @publixsubfan

[kennyweiss]

Thanks @publixsubfan -- please update the RELEASE-NOTES to reflect the bugfix

[kennyweiss]

Thanks @publixsubfan -- it looks like it covers similar/more ground, so I'm ok w/ removing the old regression case.

Did you check the bugfix against lsan and/or valgrind or a similar tool?

[publixsubfan]

@kennyweiss - yep, I tested with an lsan build with and without the bugfix commit.