main/postmarketos-base: make apk interactive by default

This would mitigate issues where apk unexpectedly replaces packages somewhat as this way the user will be able to see precisely what changes will happen to their system before they are committed. Furthermore, most users are likely accustomed to package managers like apt, dnf, pacman, among others that all are interactive by default and as such this would provide a more familiar experience for them.

This will not affected pre-existing installs, and advanced users who do not like this behaviour can restore the old one by deleting /etc/apk/interactive.