Make it possible to start a session without starting an app

[mykola-mokhnach]

I'll also add the necessary changes into xcuitest driver, so autoLaunch cap behaviour would be fixed.

[ganzf]

@mykola-mokhnach Hello,

How does this affect the following endpoint: POST /session/:session_id/appium/app/close ?
Is there any way to choose which app to close ?

EDIT: I'm wondering, what made it possible for you to implement this ? Did something change in ios test framework ? Or was it always a possibility, you simply hadn't got the time to do it ?

I've been using appium for a while and i'm only now diving into the drivers. I hope my curiosity does not bother you too much.
Thanks for your work and time !