Add base routes

ExpressAPI/src/routes/BaseRoutes.ts

+import { Express }     from 'express-serve-static-core';
+import ApiRequest      from '../models/ApiRequest';
+import express         from 'express';
+import { StatusCodes } from 'http-status-codes';
+import RoutesManager   from '../express/RoutesManager';
+
+
+class BaseRoutes implements RoutesManager {
+    private static _instance: BaseRoutes;
+
+    private constructor() { }
+
+    public static get instance(): BaseRoutes {
+        if ( !BaseRoutes._instance ) {
+            BaseRoutes._instance = new BaseRoutes();
+        }
+
+        return BaseRoutes._instance;
+    }
+
+    registerOnBackend(backend: Express) {
+        backend.get('/', (req: ApiRequest, res: express.Response) => { res.status(StatusCodes.OK).end(); });
+        backend.get('/health_check', (req: ApiRequest, res: express.Response) => { res.status(StatusCodes.OK).end(); });
+    }
+}
+
+
+export default BaseRoutes.instance;