* Unregister non-matching serviceworkers
With the addition of the /assets url, users who visited a previous
version of the site now may have two active service workers, one with
the old scope `/` and one with scope `/assets`. This check for
serviceworkers that do not match the current script path and unregisters
them.
Also included is a small refactor to publicpath.js which was simplified
because AssetUrlPrefix is always present now. Also it makes use of the
new joinPaths helper too.
Fixes: https://github.com/go-gitea/gitea/pull/15823
silverwind