Bring back navigateFallback behavior in service worker on next branch (Reverts #3419)

Created by: piotr-cz

As service workers are disabled by default by #3817 on the next branch, #3419 is probably not needed anymore.

Developers who opt in to use service workers would also expect the app to work offline when using History API like React Router or as receiver of Web Share API URLs.

mentioned in merge request !3419 (merged)

added CLA Signed label

mentioned in merge request !3924 (merged)

Created by: piotr-cz

Superseeded by #3924

closed