POC - User can create "Remind me to review content" task from post edit screen

[ilicfilip]

This is just a POC of what can be done now when we have refactored Todos into User tasks.

This PR adds a button on the Post edit screen which generates a new User (todo) task as reminder to review post content in 30 days. The task will not show up in the widget until 30 days pass.

For the purpose of this video I have changed the available_at param to be time() (without the extra 30 days), so task is visible immediately.

Screen.Recording.2025-04-03.at.13.12.56.mov

[github-actions]

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[aristath]

If we do that, we should make the TODOs snoozable - not for users but in the backend 👍
Then, we should probably hide the task until the time comes for it to be unsnoozed

EDIT: I see that's already done, so ignore previous comment

[ilicfilip]

I have merged development branch and made necessary changes, to sync this PR with the recent CPT refactor.

@aristath , I have decided to use meta_query in order not to display tasks until they are available - since we fetch user tasks only on page load it looked like a simplest solution.

Alternatively, we can use an wp_option entry to store all the task data and then create the task when available_at time is < then the current time - but to me it seemed less efficient.

[aristath]

Reminders should not be hardcoded to 30 days. User should be able to choose if they want a month, 3 months, 6 months, or a year.
When they change the reminder, we should also be checking if there's already another reminder for that post, and if so then update the existing reminder instead of creating a new one.