Require at least 1.6Gb of available RAM to install the server
    
    Verify that there is at least 1.6Gb of usable RAM on the system. Swap
    is not considered. While swap would allow a user to minimally install
    IPA it would not be a great experience.
    
    Using any proc-based method to check for available RAM does not
    work in containers unless /proc is re-mounted so use cgroups
    instead. This also handles the case if the container has memory
    constraints on it (-m).
    
    There are envs which mount 'proc' with enabled hidepid option 1
    so don't assume that is readable.
    
    Add a switch to skip this memory test if the user is sure they
    know what they are doing.
    
    is_hidepid() contributed by Stanislav Levin <slev@altlinux.org>
    
    https://pagure.io/freeipa/issue/8404
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Stanislav Levin <slev@altlinux.org>