Delete items by introducing a deleted state

When deleting items via the http api, they are not deleted anymore but
a new status "Deleted" is set. The collective insights contains now a
count separately for deleted items.

modules/restapi/src/main/resources/docspell-openapi.yml

@@ -4569,6 +4569,7 @@ components:
       required:
         - incomingCount
         - outgoingCount
+        - deletedCount
         - itemSize
         - tagCloud
       properties:
@@ -4578,6 +4579,9 @@ components:
         outgoingCount:
           type: integer
           format: int32
+        deletedCount:
+          type: integer
+          format: int32
         itemSize:
           type: integer
           format: int64