fixed react environment variables

Frontend/public/index.html

@@ -14,6 +14,7 @@
       user's mobile device or desktop. See https://developers.google.com/web/fundamentals/web-app-manifest/
     -->
     <link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
+    <script src="%PUBLIC_URL%/config.js"></script>
     <!--
       Notice the use of %PUBLIC_URL% in the tags above.
       It will be replaced with the URL of the `public` folder during the build.

Frontend/src/config.js

+const REACT_APP_API =
+  window.REACT_APP_API || "http://localhost:8080/api-service";
+const KEYCLOAK_CLIENT_ID =
+  window.KEYCLOAK_CLIENT_ID || "fairregister-development";
+
+export { REACT_APP_API, KEYCLOAK_CLIENT_ID };

Frontend/src/services/ApiService.js

 import HttpClientService from "./HttpClientService";
 import UserService from "./UserService";
 import { saveAs } from "file-saver";
+import { REACT_APP_API } from "../config";
 
-const API_URL = process.env.REACT_APP_API;
 
-const httpClient = new HttpClientService(API_URL);
+const httpClient = new HttpClientService(REACT_APP_API);
 
 
 const getUserWorkList2 = async (page, size) => {

Frontend/src/services/UserService.js

 import Keycloak from "keycloak-js";
-const CLIENT_ID = process.env.KEYCLOAK_CLIENT_ID;
+import { KEYCLOAK_CLIENT_ID } from "../config";
 
 const _kc = new Keycloak({
   url: "https://id.fairkom.net/auth",
-  clientId: CLIENT_ID,
+  clientId: KEYCLOAK_CLIENT_ID,
   realm: "fairlogin",
   "ssl-requiered": "external",
   "public-client": true,