Desktop: Allow marking sync errors as ignored in "sync status"

[personalizedrefrigerator]

Summary

This is a follow-up pull request to #10261.

Screenshot

Testing

1. Set up sync with Joplin Server.
2. Set the maximum item size to a small number (I used 4096 = 4 KiB).
3. Sync.
4. Click "View them now" on the "some items could not be synchronised" warning
5. Click "ignore" by each of the warnings.
6. Close the "some items could not be synchronised" screen.
7. Sync
8. Verify that, after syncing, the warning banner has disappeared.
9. Go to "Help > Synchronisation Status"
10. Click "retry" by each of the ignored items.
11. Sync
12. Verify that the "some items cannot be synchronised" warning is again visible.
13. Try to change the sync target.
14. Verify that changing the sync target fails.
15. Close and re-open settings.
16. Verify that the "Sync target" field is still set to "Joplin Server"
17. Close settings
18. From the sync status screen, mark all items as ignored.
19. Go to settings
20. Change the sync target.
    • Verify that this can be done successfully.
21. Sync

This has been tested successfully on MacOS Sonoma 14 4.1.