Bundle plugin files on Android

Summary: We need to tell androiddeployqt to include the plugins into the APK

Test Plan: Build plasma-phonebook with KPeopleVCard installed. KPeopleVCard and the plasma-phonebook action plugin show up in the APK

Reviewers: apol, vkrause

Reviewed By: apol

Subscribers: kde-frameworks-devel

Tags: Android, Frameworks

Differential Revision: https://phabricator.kde.org/D24024