feat(core): Set up leader selection for multiple main instances (#7527)

https://linear.app/n8n/issue/PAY-933/set-up-leader-selection-for-multiple-main-instances

- [x] Set up new envs
- [x] Add config and license checks
- [x] Implement `MultiMainInstancePublisher`
- [x] Expand `RedisServicePubSubPublisher` to support
`MultiMainInstancePublisher`
- [x] Init `MultiMainInstancePublisher` on startup and destroy on
shutdown
- [x] Add to sandbox plans
- [x] Test manually

Note: This is only for setup - coordinating in reaction to leadership
changes will come in later PRs.

packages/cli/test/unit/services/orchestration.service.test.ts

@@ -1,6 +1,6 @@
 import Container from 'typedi';
 import config from '@/config';
-import { OrchestrationMainService } from '@/services/orchestration/main/orchestration.main.service';
+import { SingleMainInstancePublisher } from '@/services/orchestration/main/SingleMainInstance.publisher';
 import type { RedisServiceWorkerResponseObject } from '@/services/redis/RedisServiceCommands';
 import { eventBus } from '@/eventbus';
 import { RedisService } from '@/services/redis.service';
@@ -12,7 +12,7 @@ import * as helpers from '@/services/orchestration/helpers';
 import { ExternalSecretsManager } from '@/ExternalSecrets/ExternalSecretsManager.ee';
 import { Logger } from '@/Logger';
 
-const os = Container.get(OrchestrationMainService);
+const os = Container.get(SingleMainInstancePublisher);
 const handler = Container.get(OrchestrationHandlerMainService);
 
 let queueModeId: string;