Fix regression reading kernel list when collecting configurations (#1846156)
    
    We have to have payload prepared to be able to read list of kernels from the
    installation source. However, during transitioning to storage module we moved
    reading list of kernels to place where the installation tasks are collected
    instead of where they are executed.
    
    Create a function which will read this list and execute everything later during
    the installation tasks execution.
    
    Resolves: rhbz#1846156