Set log folder variable to /var/log/3x-ui (#3599)

* Set log folder variable to /var/log/3x-ui

* Set log folder as x-ui and create the log folder

* Create the log folder in install and update scripts

update.sh

@@ -653,6 +653,7 @@ update_x-ui() {
     
     chmod +x /usr/local/x-ui/x-ui.sh >/dev/null 2>&1
     chmod +x /usr/bin/x-ui >/dev/null 2>&1
+    mkdir -p /var/log/x-ui >/dev/null 2>&1
     
     echo -e "${green}Changing owner...${plain}"
     chown -R root:root /usr/local/x-ui >/dev/null 2>&1