Unmount buttons when corresponding screen is unmounted
Currently buttons were unmounted each time a screen was pushed to the stack.
As we're clearing props when screens are unmounted from the prop store - when a screen
was popped to - its buttons's props were undefined.
This commit changes things so that buttons are unmounted when buttons are set
using mergeOptions and when the corresponding screen is unmounted.
* Migrate to jest to support parallel ios simulator from detox
* When e2e lint only ts or js files
* Remove mocha from deps and decrease from 480000ms to 180000ms