Fix local only tasks sync

[opatry]

Description

There were several issues:

• local list id not properly managed to link to remote id (leading to task being moved in default list)
• notes, due date and other fields weren't transfered from local to remote task
• no proper dispatch of IO thread for API calls
• syncing local only completed lead to weird remote task status (completed but not hidden, position not following the 099999 pattern
• local only task processing was also made several times not taking into account the associated task list

Took the opportunity of these change to distinguish insert from update (using upsert pattern in such a case).
Also added TaskList & Task factories avoiding the use of read only/output only fields of the API data class bindings.

Checklist

• I have read the CONTRIBUTING guide
• Code compiles correctly
• Created tests which fail without the change (if possible)
• All tests passing