layout change UI (#776)

* add layout to schema

* add layout choice action and reducer

* multi layout UI

* update unit tests

* add missing file

* update test schema

* fix duplicate test id

* fix tabs

* PR lint

* fix pytest

server/test/schema.json

@@ -47,5 +47,14 @@
         "type": "int32"
       }
     ]
+  },
+  "layout": {
+    "obs": [
+      {
+        "name": "umap",
+        "type": "float32",
+        "dims": ["umap_0", "umap_1"]
+      }
+    ]
   }
 }