Add redux-logger.

This automatically logs state changes (in a readable form) to the js
console. We'll probably want to turn this off in production to cut down
on log noise.

client/src/app/store.ts

@@ -4,6 +4,7 @@ import frontLinesReducer from "../api/frontLinesSlice";
 import supplyRoutesReducer from "../api/supplyRoutesSlice";
 import tgosReducer from "../api/tgosSlice";
 import { Action, ThunkAction, configureStore } from "@reduxjs/toolkit";
+import logger from "redux-logger";
 
 export const store = configureStore({
   reducer: {
@@ -13,6 +14,8 @@ export const store = configureStore({
     supplyRoutes: supplyRoutesReducer,
     tgos: tgosReducer,
   },
+  // The logger middleware must be last or it won't log actions.
+  middleware: [logger],
 });
 
 export type AppDispatch = typeof store.dispatch;