[Feature Request] Implement GUI for lists and tasks trashbin

[raimund-schluessler]

see nextcloud/server#1662

[bcutter]

+10

[teneighty-yvr]

I would be satisfied with a sanity check by an "are you sure?" prompt. (edit: separate issue #1408)

A trashbin is better because you can restore deleted tasks a day or a week later, maybe more, which can definitely happen for some users. I use an archive list instead, but I have deleted a task by accident. A trashbin implementation would also by nature be likely to protect other applications accessing tasks through DAV, but that might be in nextcloud/server scope? (edit: nextcloud/server changes required)

Just to add how important tasks are for my use case, I use them a lot in the project management field in a construction contracting company with million dollar projects. Maybe there are better ways but this is simple, standardized, portable, open source, we use Nextcloud anyway for files, and tasks is working really well for me. I keep a lot of notes in each tasks. A lot. Checklist (thank you markdown), progress, developments, who I need to follow up with and when. Often these notes span several months. Losing one task to a mis-click can be a very big deal.

Nextcloud/server : 20.0.5
Tasks : 0.13.6