Modal (Alert) when a project or asset fails to save

[rschamp]

Part of #3723

In any case where the project fails to save, we should display a modal to the user while we begin retrying.

The modal should have a button which will download the SB3 of the project to the user's computer.

[kaaaaathy]

BTW, here's one example of how we could do an alert. Can change the language to be more generic.

This would appear after a few (currently it's 3?) failed saves. The timer will keep counting down in the nav...

I changed the title of the issue after our chat today - just to clarify the UI element that would be ideal design-wise 👍

[kaaaaathy]

After talking to @carljbowman and @paulkaplan, decided to go with this UX + language:

UX for save error

1. The system will keep trying to autosave, and go through this countdown process 3 times...
   

2. After 3 failed attempts, fire this alert. We should still be checking periodically for reconnection as often as possible, but users have the option to "Try Again" immediately or "Download."
   

3. After either clicking "Try Again" or once we can detect reconnection, then fire this alert instead...
   
   (If it fails, go back to alert in Complaints about react dependencies #2.)

4. Alert disappears. Project immediately saves, using the title bar convention.
   

5. If save succeeds, show this after 1-2 seconds.
   
   If save fails (for some reason), revert to Design #1.

[benjiwheeler]

A note from discussion with @kathymakes -- we may want to make the #3 "Reconnecting..." alert appear for a set number of seconds, before returning to #2 "Project could not save" alert. This might require setting alerts to specifically only show one at a time (like inline menu bar alerts do)