Upgrade Web UI to Create-React-App 4 and React 17 (#1105)

* Upgrade to CRA 4.0.3

* Try to fix tests. No lucky

* Fix new ESLint errors

* Fix JS tests and remove unwanted dependency. (#1106)

* Fix tests

* Fix lint

* Remove React v16 workaround (fixed in v17)

* Force eslint to break on warnings

* Lint now needs to be called explicitly in the pipeline

Co-authored-by: Yash Jipkate <34203227+YashJipkate@users.noreply.github.com>

ui/src/themes/useCurrentTheme.js

@@ -4,7 +4,7 @@ import themes from './index'
 import { AUTO_THEME_ID } from '../consts'
 import config from '../config'
 
-export default () => {
+const useCurrentTheme = () => {
   const prefersLightMode = useMediaQuery('(prefers-color-scheme: light)')
   return useSelector((state) => {
     if (state.theme === AUTO_THEME_ID) {
@@ -19,3 +19,5 @@ export default () => {
     return themes[themeName]
   })
 }
+
+export default useCurrentTheme