feat(core): Coordinate workflow activation in multiple main scenario in internal API (#7566)

Story: https://linear.app/n8n/issue/PAY-926

This PR coordinates workflow activation on instance startup and on
leadership change in multiple main scenario in the internal API. Part 3
on manual workflow activation and deactivation will be a separate PR.

### Part 1: Instance startup

In multi-main scenario, on starting an instance...
- [x] If the instance is the leader, it should add webhooks, triggers
and pollers.
- [x] If the instance is the follower, it should not add webhooks,
triggers or pollers.
- [x] Unit tests.

### Part 2: Leadership change 

In multi-main scenario, if the main instance leader dies…

- [x] The new main instance leader must activate all trigger- and
poller-based workflows, excluding webhook-based workflows.
- [x] The old main instance leader must deactivate all trigger- and
poller-based workflows, excluding webhook-based workflows.
- [x] Unit tests.

To test, start two instances and check behavior on startup and
leadership change:

```
EXECUTIONS_MODE=queue N8N_LEADER_SELECTION_ENABLED=true N8N_LICENSE_TENANT_ID=... N8N_LICENSE_ACTIVATION_KEY=... N8N_LOG_LEVEL=debug npm run start

EXECUTIONS_MODE=queue N8N_LEADER_SELECTION_ENABLED=true N8N_LICENSE_TENANT_ID=... N8N_LICENSE_ACTIVATION_KEY=... N8N_LOG_LEVEL=debug N8N_PORT=5679 npm run start
```

packages/cli/src/services/orchestration.base.service.ts

@@ -2,8 +2,9 @@ import Container from 'typedi';
 import { RedisService } from './redis.service';
 import type { RedisServicePubSubPublisher } from './redis/RedisServicePubSubPublisher';
 import config from '@/config';
+import { EventEmitter } from 'node:events';
 
-export abstract class OrchestrationService {
+export abstract class OrchestrationService extends EventEmitter {
 	protected initialized = false;
 
 	protected queueModeId: string;
@@ -29,6 +30,7 @@ export abstract class OrchestrationService {
 	}
 
 	constructor() {
+		super();
 		this.redisService = Container.get(RedisService);
 		this.queueModeId = config.getEnv('redis.queueModeId');
 	}

packages/cli/src/services/orchestration/main/MultiMainInstance.publisher.ee.ts

@@ -13,11 +13,11 @@ export class MultiMainInstancePublisher extends SingleMainInstancePublisher {
 
 	private leaderId: string | undefined;
 
-	public get isLeader() {
+	get isLeader() {
 		return this.id === this.leaderId;
 	}
 
-	public get isFollower() {
+	get isFollower() {
 		return !this.isLeader;
 	}
 
@@ -84,6 +84,8 @@ export class MultiMainInstancePublisher extends SingleMainInstancePublisher {
 
 			this.leaderId = this.id;
 
+			this.emit('leadershipChange', this.id);
+
 			await this.redisPublisher.setExpiration(this.leaderKey, this.leaderKeyTtl);
 		}
 	}