Fix not being able to dismiss new login toasts
Fix not being able to dismiss new login toasts

`toastKey` is a thing.

Fixes https://github.com/vector-im/riot-web/issues/13923

(cherry picked from commit c667ea69afba22620e0add944bdf0b4c22a5a184)

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk