[functional][u] Make pkcon / packagekit installation test more explicit
On font changes like introduced by
many openQA tests fail and some even in very obscure way because the previous needles for an older font do not match anymore in an annoying way, hidden behind a job timeout or that the screen lock kicks in. Problem is that we use "pkcon install" here and need to check for both the exit status as well as for needles to handle the policykit based authentication windows. We thought about executing that only in an explicit test module and using zypper otherwise.
However, that would not reduce the number of needles necessary to maintain, only make it more explicit what is happening
AC1: seperate testmodule to test pkcon is added
AC2: all current scenarios which use pkcon are adapted to use zypper_call instead