tauri: App crashes at startup when no internet

[filopedraz]

Description

If no internet, the app doesn't even load.

[Janaka-Steph]

We fetch service infos from registry in setup hook of main.rs. The hook happens before app loading. Not sure how to improve UX here.

[tiero]

Let's expose a command is_offline and an event as well to JS so the app che show a nice "You are offline" screen