Create test for rawhide signatures check
    
    Should prevent usual broken signatures after new version branch.
    Tests possible enablement from stable branch and upgrade. It should work
    without GPG validation disabled.
    
    Add STI entry for new test
    
    Adds fmf and tmt support.
    
    Remove RHTS dependencies
    
    Workaround on platforms, where $basearch != $(arch)
    
    i686 has a key on i386. Those platforms are not the same.
    
    Use dnf to obtain basearch in test
    
    Keep using just coreutils in spec, dnf build dependency might create
    circular dependencies.
    
    Signed-off-by: Petr Menšík <pemensik@redhat.com>