add: new openwrt configuration

shortened hiddify-core to hiddify for simplicity.
removed options workingdir and user as it is not being used at the 
moment also we need root privilege for tun.
added new option "config" referring to config file or url after -c switch.
introduced option "appconfig" referring to app config file or url
 after -d switch.

hiddify-cli run -c <config file or sublink> -d <HiddifyApp config file 
or URL>
https://hiddify.com/app/HiddifyCli-guide/#

wrt/files/hiddify.conf

@@ -0,0 +1,4 @@
+config hiddify 'main'
+	option enabled '0'
+	option config '/config/file/or/sublink'
+	option appconfig '/etc/hiddify/appconfig.json'