kdumpctl: merge check_current_{kdump,fadump}_status
    
    Resolves: bz2232499
    Upstream: Fedora Rawhide
    Conflict: Some newer patches has been rebased, which caused git am to
    encounter some problems.
    
    commit b9fd7a4076a2b355f57c7c2529a093f3aa9f6863
    Author: Philipp Rudo <prudo@redhat.com>
    Date:   Thu Jan 12 16:31:02 2023 +0100
    
        kdumpctl: merge check_current_{kdump,fadump}_status
    
        Both functions are almost identical. The only differences are (1) the
        sysfs node the status is read from and (2) the fact the fadump version
        doesn't verify if the file it's trying to read actually exists. Thus
        merge the two functions and get rid of the check_current_status wrapper.
    
        While at it rename the function to is_kernel_loaded which explains
        better what the function does.
    
        Finally, after moving FADUMP_REGISTER_SYS_NODE shellcheck can no longer
        access the definition and starts complaining about it not being quoted.
        Thus quote all uses of FADUMP_REGISTER_SYS_NODE.
    
        Signed-off-by: Philipp Rudo <prudo@redhat.com>
        Reviewed-by: Coiby Xu <coxu@redhat.com>
    
    Signed-off-by: Lichen Liu <lichliu@redhat.com>