register 'archived' to project anatomy schema

So the settings can recognize and won't pop warnings

openpype/settings/defaults/project_anatomy/attributes.json

@@ -23,5 +23,6 @@
         "unreal/4-26"
     ],
     "tools_env": [],
-    "archive_confirm": ""
+    "archive_confirm": "",
+    "archived": false
 }

openpype/settings/entities/schemas/projects_schema/schemas/schema_anatomy_attributes.json

@@ -75,6 +75,11 @@
             "key": "archive_confirm",
             "label": "Archive Project",
             "placeholder": "Input project name to confirm archiving."
+        },
+        {
+            "type": "boolean",
+            "key": "archived",
+            "label": "Is Archived"
         }
     ]
 }