fix(task-manager): delay on migration of task notifications

Issue addressed #1244 (closed)

Currently, the task notifications were fetched in order of created date, to avoid re-ordering each time they're updated.

The only case where it failed was, when we copy all the task notifications from the task builder to the task manager, upon selection or submission of the manuscript. In this, the created date was the same for some task notifications, and the sorted order was not fixed. With each update in the UI, was fetching data from the backend in a random way, and thus reordering them in UI.

With this fix, each task notification corresponding to a task will be inserted with a delay of 100ms, providing a unique created date for each task notification and fixing the reordering bug upon making any updates.