Add workflow and version as standard object (#6412)

As title

Hidden behind a feature flag.

packages/twenty-server/src/engine/core-modules/feature-flag/feature-flag.entity.ts

@@ -25,6 +25,7 @@ export enum FeatureFlagKeys {
   IsMessagingAliasFetchingEnabled = 'IS_MESSAGING_ALIAS_FETCHING_ENABLED',
   IsGoogleCalendarSyncV2Enabled = 'IS_GOOGLE_CALENDAR_SYNC_V2_ENABLED',
   IsFreeAccessEnabled = 'IS_FREE_ACCESS_ENABLED',
+  IsWorkflowEnabled = 'IS_WORKFLOW_ENABLED',
 }
 
 @Entity({ name: 'featureFlag', schema: 'core' })