use the new install_package form

Summary:
plasmoids can now be used also from binary resource files rcc
which makes a bit of difference in startup times especially on
devices with low storage
use the new macro to generate and install the rcc

Test Plan: still works

Reviewers: #plasma

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D11551