Fixes a bug where clicking the ownCloud logo on a public link page would lead to certain UI elements being duplicated.

This happens because some extensions and extension points are being registered more than once because the application layout gets unmounted on mounted again when clicking the logo. The solution is to properly unregister those extensions on unmount.

Prevents all apps from re-initializing when clicking the ownCloud logo on public link pages.

The issue happens because clicking the logo navigates the user to the `resolvePublicLink` page, which results in the public context being reset. We can omit this reset in that case though because we can guarantee that the user will either land on a public page, or on some other route which then resets the context anyways.