Answer handling improvements

[smadbe]

Description

Fixes several issues with answer saving: 1) if there is a change when changing task, it should be saved (was not if we hadn't waiting the 60sec delay) 2) on submit, there should be a current answer save (was not if we hadn't waiting the 60sec delay)

Recommendation: test it on https://dev.algorea.org/branch/answer-handling-improvements/en/a/773396873861865944;p=4702,7528142386663912287,7523720120450464843;a=0

You can see if a change as been saved because 1) you see the call (PUT), 2) if you refresh the page, you see the change

Test cases

• there is no save at task launch
• if there is change immediately, it is saved by autosave
• if there one failed auto save (every 60sec), a message is displayed, but it is retried at the next interval
• if there is no change, no autosave is done
• submitting triggers a current state save
• changing task triggers a (visible) current state save when the state has changed
  • if this save fails, the user can choose to retry
  • if this save fails, the user can choose to loose changes
• changing task does not trigger a current state save when the state has not changed
  • even just after the app was launched (past bug: was saving just after app launch if even if no change)
• on a task which cannot be loaded (e.g., https://dev.algorea.org/branch/answer-handling-improvements/en/a/1414822370876733593;p=4702,100575556387408660,1788359139685642917;pa=0), the next-prev navigation still work (may be blocked by unload protection if buggy)
• if I change task while the autosave is request is running, the "current" answer must still have been saved somehow

[Iloveall]

When saving, and you click navigate to another item - it will save again as lot as you clicking

https://github.com/user-attachments/assets/9cd07cae-eebd-47a0-a03f-2f139cc55f66

[smadbe]

When saving, and you click navigate to another item - it will save again as lot as you clicking Screen.Recording.2024-11-06.at.5.14.19.PM.mov

I thought about it. It is not a big deal and it would be quite difficult to fix. So let's keep it as it is.