Put workfows behind a feature flag (#6417)

We have recently merged
[#workflow](https://github.com/twentyhq/twenty/pull/6412) but we should
put the workflow standard object behind a feature flag for now

---------

Co-authored-by: bosiraphael <raphael.bosi@gmail.com>

packages/twenty-server/src/engine/twenty-orm/interfaces/workspace-index-metadata-args.interface.ts

@@ -1,3 +1,5 @@
+import { Gate } from 'src/engine/twenty-orm/interfaces/gate.interface';
+
 export interface WorkspaceIndexMetadataArgs {
   /**
    * Class to which index is applied.
@@ -14,4 +16,9 @@ export interface WorkspaceIndexMetadataArgs {
    * Index columns.
    */
   columns: string[];
+
+  /**
+   * Field gate.
+   */
+  readonly gate?: Gate;
 }