IPoE-server add the ability to configure LUA scripts and username
```
[ipoe]
lua-file=/config/accel-ppp/ipoe.lua
interface=eth1,shared=1,mode=L2,ifcfg=1,start=dhcpv4,ipv6=1,username=lua:username_func
```
Allow to add configuration path to the LUA script
Example of the lua file:
```
#!lua
function username_func(pkt)
local username=pkt:hwaddr()
return username
end
```
Proposed CLI:
```
set service ipoe-server lua-file <path_to_lua_file>
set service ipoe-server interface eth1 lua username <username_func>
```
https://docs.accel-ppp.org/examples/lua_examples.html