Warn user about sync unavailable

[cmonfortep]

Task/Issue URL: https://app.asana.com/0/1149059203486286/1207374369607209/f

Description

It might be that clients are rejected by the BE if they trigger too many requests within a threshold, or server is a teapot. In that case we want to warn the user if 10 consecutive calls are rejected, or if after a failure there is no success sync in 12h. (notified once per day)

Steps to test this PR

Feature 1

• [x] Fresh install
• [x] create a sync account
• [x] no errors, no notifications
• [x] add a bookmark or a credential
• [x] no warnings visible
• [x] (enable notification permissions)
• [x] apply patch attached to Asana and install
• [x] opening the app will trigger sync (it has started failing, hold on)
• [x] if you wait a few seconds you will get a notification (the scheduled worker in the patch has 12 seconds delay)
• [x] ensure you got a notification
• [x] Go to sync settings, ensure there's a warning "sync & backup is temporarily unavailable"
• [x] discard patch and install app
• [x] when opening the app, sync will succeed
• [x] Ensure warning is gone

( optional tests)

• [ ] disable sync
• [ ] enable sync again (just to start from a clean state, so we see the notification)
• [ ] apply patch again, but discard the change in RealSyncUnavailableRepository using HOURS instead of Seconds
• [ ] update the app
• [ ] perform actions until you hit 10 failures on sync
• [ ] At some point you get a notification and validate warning is in settings

UI changes

Before	After
!(Upload before screenshot)	(Upload after screenshot)

[cmonfortep]

• #4571 : 2 dependent PRs (#4575 , #4589 ) 👈
• #4570
• #4569
• develop

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