Refactor invoke queue into promise queue and support inline awaits

[talkol]

All lines in a test scenario are naturally asynchronous since the device has to perform each interaction and that takes time. In order to avoid the boilerplate of writing await before every line, we use a concept similar to what protractor does for its Control Flow.

Unlike protractor, our current implementation simply manages an invocation queue and then executes it until the test terminates.

This is not ideal. We need to switch to a pending promise queue like protractor.

In addition, we want to support a manual inline await in the middle of a test. The reason is that you might want to wait on something external, for example restart the simulator in the middle of a test.

[rotemmiz]

async await api rewrite is now in master, and will be published soon with detox 5.0.0.
We ditched the Control Flow idea in favor of native constructs (Promises and async await). there is no invoke queue anymore. checkout the test project