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/workflow/src/Interfaces.ts

@@ -1905,7 +1905,14 @@ export type WorkflowExecuteMode =
 	| 'retry'
 	| 'trigger'
 	| 'webhook';
-export type WorkflowActivateMode = 'init' | 'create' | 'update' | 'activate' | 'manual';
+
+export type WorkflowActivateMode =
+	| 'init'
+	| 'create'
+	| 'update'
+	| 'activate'
+	| 'manual'
+	| 'leadershipChange';
 
 export interface IWorkflowHooksOptionalParameters {
 	parentProcessMode?: string;