relocate repo files so ND2 is the only code

lib/App/Netdisco/DB/schema_versions/App-Netdisco-DB-20-21-PostgreSQL.sql

@@ -0,0 +1,10 @@
+BEGIN;
+
+CREATE UNIQUE INDEX jobs_queued ON admin (
+  action,
+  coalesce(subaction, '_x_'),
+  coalesce(device, '255.255.255.255'),
+  coalesce(port, '_x_')
+) WHERE status LIKE 'queued%';
+
+COMMIT;