register header and footer in theme json (#5441)

blockbase/theme.json

@@ -25,6 +25,14 @@
 		{
 			"name": "header-wide",
 			"area": "header"
+		},
+		{
+			"name": "header",
+			"area": "header"
+		},
+		{
+			"name": "footer",
+			"area": "footer"
 		}
 	],
 	"customTemplates": [