Automatically discover test suites about cli-test-intern

[rorticus]

Looking to get some discussion on this, but I think we might want to add a parameter or something that would generate the tests/unit/all.ts file. Maybe something like dojo test --discover or something. While we don't even really need an all.ts file for testing via node, the dojo build -m tests command expects actual files in the tests/unit directory so if we want to work with the existing build stuff, we'll probably want to actually generate the all.ts file and maybe add it to .gitignore?

[rorticus]

So.. added spec.ts globs to cli-build-app and cli-build-widget. That means that the only discovery we need to do here is when running via node we can use a glob. No need to actually create files.