refactor(core): Use mixins to delete redundant code between Entity classes (no-changelog) (#6616)

* db entities don't need an ID before they are inserted

* don't define constructors on entity classes, use repository.create instead

* use mixins to reduce duplicate code in db entity classes

packages/cli/test/integration/shared/testDb.ts

@@ -19,7 +19,7 @@ import { InstalledPackages } from '@db/entities/InstalledPackages';
 import type { Role } from '@db/entities/Role';
 import type { TagEntity } from '@db/entities/TagEntity';
 import type { User } from '@db/entities/User';
-import { WorkflowEntity } from '@db/entities/WorkflowEntity';
+import type { WorkflowEntity } from '@db/entities/WorkflowEntity';
 import { RoleRepository } from '@db/repositories';
 import type { ICredentialsDb } from '@/Interfaces';
 
@@ -412,7 +412,7 @@ export async function createManyWorkflows(
 export async function createWorkflow(attributes: Partial<WorkflowEntity> = {}, user?: User) {
 	const { active, name, nodes, connections } = attributes;
 
-	const workflowEntity = new WorkflowEntity({
+	const workflowEntity = Db.collections.Workflow.create({
 		active: active ?? false,
 		name: name ?? 'test workflow',
 		nodes: nodes ?? [