Add login-username support

Shown for the "Username Form" login step.

I would also like to work on:
- `login-password.ftl`
- `webauthn-authenticate.ftl`

But first want to see opinions on this!

package.json

@@ -59,6 +59,7 @@
         "react": "^16.8.0 || ^17.0.0 || ^18.0.0"
     },
     "devDependencies": {
+        "@babel/core": "^7.0.0",
         "@emotion/react": "^11.4.1",
         "@types/memoizee": "^0.4.7",
         "@types/minimist": "^1.2.2",