add cow_label and cow_directory options to the global scope of the yaml config file

Allows to set to set the persistent backing store options via the yaml config too and
not only through boot commandline options.

airootfs/usr/bin/sysrescue-configuration.lua

@@ -264,6 +264,8 @@ end
 
 cmdline_options = {
     ['copytoram'] = "global",
+    ['cow_label'] = "global",
+    ['cow_directory'] = "global",
     ['checksum'] = "global",
     ['loadsrm'] = "global",
     ['dostartx'] = "global",

patches/archiso-v43-07-yaml-config.patch

@@ -2,7 +2,7 @@ diff --git a/archiso/initcpio/hooks/archiso b/archiso/initcpio/hooks/archiso
 index 853652e..53215eb 100644
 --- a/archiso/initcpio/hooks/archiso
 +++ b/archiso/initcpio/hooks/archiso
-@@ -197,6 +197,39 @@ archiso_mount_handler() {
+@@ -197,6 +197,60 @@
          fi
      fi
  
@@ -39,6 +39,27 @@ index 853652e..53215eb 100644
 +        fi
 +    done
 +
++    # read string values set by YAML config, only handle non-empty strings
++    for curentry in "cow_label" "cow_directory"
++    do
++        if value=$(jq --raw-output ".global.${curentry} // empty | tostring" ${jsonconfig} 2>/dev/null)
++        then
++            if [[ -n "${value}" ]] ; then
++                eval "${curentry}='${value}'"
++            fi
++        fi
++    done
++
++    # redo handling of cow_label, it could have changed due to yaml config
++    if [[ -n "${cow_label}" ]]; then
++        cow_device="/dev/disk/by-label/${cow_label}"
++        [[ -z "${cow_persistent}" ]] && cow_persistent="P"
++    elif [[ -n "${cow_device}" ]]; then
++        [[ -z "${cow_persistent}" ]] && cow_persistent="P"
++    else
++        cow_persistent="N"
++    fi
++    
      if [[ "${checksum}" == "y" ]]; then
          if [[ -f "/run/archiso/bootmnt/${archisobasedir}/${arch}/airootfs.sha512" ]]; then
              msg -n ":: Self-test requested, please wait..."