refactor(core): Make workflow services injectable (no-changelog) (#8033)

Refactor static workflow service classes into DI-compatible classes

Context: https://n8nio.slack.com/archives/C069HS026UF/p1702466571648889

Up next:
- Inject dependencies into workflow services
- Consolidate workflow controllers into one
- Make workflow controller injectable
- Inject dependencies into workflow controller

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Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

packages/cli/test/integration/ActiveWorkflowRunner.test.ts

@@ -24,11 +24,13 @@ import { setSchedulerAsLoadedNode } from './shared/utils';
 import * as testDb from './shared/testDb';
 import { createOwner } from './shared/db/users';
 import { createWorkflow } from './shared/db/workflows';
+import { WorkflowService } from '@/workflows/workflow.service';
 
 mockInstance(ActiveExecutions);
 mockInstance(ActiveWorkflows);
 mockInstance(Push);
 mockInstance(SecretsHelper);
+mockInstance(WorkflowService);
 
 const webhookService = mockInstance(WebhookService);
 const multiMainSetup = mockInstance(MultiMainSetup, {