fix(startingpoint): add get_config_value and set_config_value to ublue-update.sh (#37)

modules/bling/installers/ublue-update.sh

@@ -3,6 +3,15 @@
 # Tell build process to exit if there are any errors.
 set -oue pipefail
 
+get_config_value() {
+    sed -n '/^'"$1"'=/{s/'"$1"'=//;p}'
+}
+
+set_config_value() {
+    CURRENT=$(get_config_value $1 $3)
+    sed -i 's/'"$1"'='"$CURRENT"'/'"$1"'='"$2"'/g' $3
+}
+
 # Check if ublue-os-update-services rpm is installed, these services conflict with ublue-update
 if rpm -q ublue-os-update-services > /dev/null; then
     rpm-ostree override remove ublue-os-update-services