BE: Add status widget to issues

Issues and epics are part of the GA release for custom status. So we need to add the status widget for these types.

We want to dogfood status only on tasks, so we need to ensure the widget is not visible for issues~~ and epics~~.

Update: We decided not to include epics right now. It depends on a) capacity and b) the state of new work item boards.

Proposal

1. Either introduce a new feature flag work_item_status_on_tasks or reuse the work_items_beta FF to guard all code paths that are required for system-defined status on tasks. It's important to note that the work_item_status_feature_flag should not be enabled to use status on tasks. See separate issue for this Move task-related functionality under work_item... (#541079 - closed)
2. Add the status widget to issues
3. Regardless of license and FF, add the initial status on item creation and perform transitions when the state changes. Handled with BE: Set Status automatically for open/close/dup... (#498394 - closed)
4. Backfill status for open issues~~ and epics~~. Handled with BE: Backfill status data for the existing work ... (#498395)