Refactor impersonation mode into guard

apps/api/src/app/access/access.controller.ts

@@ -1,3 +1,4 @@
+import { AllowDuringImpersonation } from '@ghostfolio/api/decorators/allow-during-impersonation.decorator';
 import { HasPermission } from '@ghostfolio/api/decorators/has-permission.decorator';
 import { HasPermissionGuard } from '@ghostfolio/api/guards/has-permission.guard';
 import { ConfigurationService } from '@ghostfolio/api/services/configuration/configuration.service';
@@ -26,6 +27,7 @@ import { StatusCodes, getReasonPhrase } from 'http-status-codes';
 
 import { AccessService } from './access.service';
 
+@AllowDuringImpersonation()
 @Controller('access')
 export class AccessController {
   public constructor(