refactoring: move sql files

resources/sql/functions/citizen/find_citizen_by_id.sql

@@ -0,0 +1,17 @@
+create or replace function find_citizen_by_id(in id uuid, out resource json) language plpgsql as
+$$
+declare
+    _id alias for id;
+begin
+    select to_json(t) into resource
+    from (
+         select 
+            z.*, 
+            find_user_by_id(z.user_id) as "user"
+         from citizen as z
+         where z.id = _id
+     ) as t;
+end;
+$$;
+
+-- drop function if exists find_citizen_by_id(uuid, inout json);