Restore task purge support

[huantrinh1802]

• What command(s) did you run?
  task status:deleted purge
• What did you expect to happen?
  In v2.x, it works. In v3, it prints out

Deleted tasks are removed from the task list automatically after they expire

• Why I need this?

  • I am writing a neovim plugin for interacting with Taskwarrior so I often create dummy tasks to test.
  • Often I make a mistake, I will delete the task then reuse the previous command with correct info
  • It would be great to not see the deleted ones when running all report :)

[djmitche]

At the moment, expiration occurs automatically at 180 days after the last modification of a task.

Deletion is a little bit risky from the perspective of the sync model -- if there's another replica out there with changes to the deleted task, the task will end up out-of-sync between the two replicas -- but that's a tolerable risk when testing, for example. So, maybe we can add that support with that caveat documented somewhere.

[djmitche]

This will require GothenburgBitFactory/taskchampion#383

[CorentinJ]

In testing some scripts I generated over 1,000 tasks. I deleted them, but they still clutter the database and make debugging harder. I would love to have a command to effectively remove them entirely.