Pass interactive flag to triggers
It would be nice for triggers to know if apk is run interactively. That would allow triggers to provide some user choice if they want to do something or not. eg. grub trigger.
I think an environmental variable would be the best way. APK_IS_INTERACTIVE=1
maybe. I think that the name makes clear that this is not a variable to make apk interactive.
This doesn't work with parallel triggers (#10760). So if they are added that would need to be disabled in interactive mode.
Idea comes from aports#15653 since it would benefit from interactivity when possible.