Add cancel button to configure Action extension

[zzebrum]

1. Install AG but do not run it
2. go to Safari and try to use Action extension

Actual behavior:
https://uploads.adguard.com/Screenshot_2019-06-05_at_18.04.41_2019-07-04_19-42-10.png

Expected behavior: an option to exit the screen (:

[AlikhanAliev]