Replace Inbox with in-client registration of export tasks and results

[lexvand]

The inbox is not available for anonymous users. And it has the issue that it is emptied when going to the Django admin or the management pages.

Solution:

• The client keeps track of task-URLs of each task it starts, and a timestamp of when the task was started.
• Every x seconds, the task-URL of unfinished tasks is polled to see what the status is. Finished tasks are marked as such, and the result can be downloaded.
• After time has passed (2 weeks?), the tasks are forgotten.
• This will work identically for all users, logged in or not.
• Lizard-catalog will not use the Inbox at all anymore.
• The UI should not visibly change
• This part of the Redux state (information about requested export tasks) will be mirrored in LocalStorage so that it is still available if the user leaves the page and returns later. There is probably some external library for it, not decided yet whether we prefer using one or rolling our own for simplicity.
• What if a logged-in user requests exports, and then logs out so he doesn’t have access to his exports anymore (Actually, is that a thing? There may not be any security on export downloads at all, apart from needing the URL).

Also see https://nelen-schuurmans.atlassian.net/browse/BACK-613 ; if the backend adds a required User field to tasks, running tasks as an anonymous user would not be possible at all anymore. So they need to take this requirement into account.

[FRNT-643] created by lex.vandolderen

[lexvand]

Remco Gerlich Could you estimate this issue so we can discuss when to plan it?

by lex.vandolderen

[lexvand]

Maybe 2 days. The last point about storing to localStorage excluded; we haven’t done that before, but we will use it in 3Di as well so in a few weeks we’ll know how easy it is.

by remco.gerlich