[Discussion] Quality Assurance Discipline

Unit testing and quality assurance are two very different things. I might summarize the most important differences as:

- A QA test is written based on the behavior defined in the documentation. Any behavior that doesn't agree with the documentation is a bug. Said bug could be in the code, the documentation, or even the test itself; some triage may be necessary.
- A QA test can operate at any level of the stack. Everything from the behavior of the API to the behavior of the GUI is fair game.
- A QA test can be written in response to an issue.
- A QA member would report bugs in the issue tracker. If they can also fix it, great! This shouldn't be expected. Bug reporting can sometimes be automated.
- QA test suites can be automated but this is often done outside of the continuous integration system.
- QA can be coordinated with Release Engineering. The QA team would run their test suites and "authorize" a release.
- A QA discipline adds process. Coordination between core developers/release engineering/quality assurance is important.

I've put together #3 as an example of a very basic QA test. It can be run from the command line or integrated into a future test harness. If you'd like to help shape what a QA test might look like in Godot, please chime in on the PR. I'm cataloging implementation issues there.