initial integration lua language to psql

It can looks like

(2026-08-06 17:44:32) postgres=# \luacode 
Enter code to be copied followed by a newline.
End with a backslash and a period on a line by itself, or an EOF signal.
>> function x(n)
>>   return n + 10
>> end
>> \.
(2026-08-06 17:45:32) postgres=# \luacode
Enter code to be copied followed by a newline.
End with a backslash and a period on a line by itself, or an EOF signal.
>> print (x(10))
>> \.
20

https://github.com/okbob/lua-psql