Lua /etc/resolv.conf parser and some refactoring

rootfs/etc/nginx/lua/test/run.lua

@@ -11,6 +11,7 @@ do
   -- if there's more constants need to be whitelisted for test runs, add here.
   local GLOBALS_ALLOWED_IN_TEST = {
     _TEST = true,
+    helpers = true,
   }
   local newindex = function(table, key, value)
     rawset(table, key, value)
@@ -33,6 +34,8 @@ do
   setmetatable(_G, { __newindex = newindex })
 end
 
+_G.helpers = require("test.helpers")
+
 
 local ffi = require("ffi")
 local lua_ingress = require("lua_ingress")