chore: re-organize test app

[dopry]

• move example to test/testapp
• consolidate tests in one location

[dopry]

@zerolab I'd love to get this in pronto so we're not blocking other PRs that may be implementing tests. I know we've requested tests on a few open PRs.

[zerolab]

@dopry did a quick first pass and left a couple of notes

[dopry]

@zerolab I think I've addressed all the issues. This should be ready to review again.

[zerolab]

Let's get this in.