Googletest: Computable results

[maxitg]

Changes

• Stores results of libSetReplace tests in the new TestResults directory as JUnit XMLs.
• This allows Circle CI to pick up these results and display them in a nice way.

Comments

• The same can be done for Wolfram Language as well. We will need to produce the XMLs manually, but we can infer the format from the files generated by Googletest.

Examples

• This is what it looks like when tests pass.
• And this is when they fail.

---

This change is 

[maxitg]

There was a conflict in the YAML file because the Windows job and the store_test_results step were next to each other.