feature #4: create function for constitution and title (not article in title)

resources/functions/constitution/find_constitution_by_id.sql

@@ -0,0 +1,19 @@
+create or replace function find_constitution_by_id(in id uuid, out resource json) language plpgsql as
+$$
+declare
+    _id alias for id;
+begin
+    select to_json(t)
+    from (
+        select
+            c.*,
+            find_citizen_by_id(c.created_by_id) as created_by,
+            find_constitution_titles_by_id(c.id) as titles
+        into resource
+        from constitution as c
+        where c.id = _id
+    ) as t;
+end;
+$$;
+
+-- drop function if exists find_constitution_by_id(uuid, out json);