[sle15sp1][desktop] Implement test cases for gnome-software/gnome-package-kit/packagekit.
We have been lack of checking the packagekit mechanism in early development phase, and experienced some tough time to do a thorough check in the past.
Automating such a scenario on one hand will make sure the toolset is tested in early development, on the other hand, it will remind us update-test-*
should be ready in early development phase.
Notice the update-test-* packages will be intended to remove in GMC. So the case is supposed to be failed (or softfailed) in GMC build.