Form builder - ability to archive (trash/hide) form submissions

Is your proposal related to a problem?

• The form builder feature is an incredible part of Wagtail that allows for easy to build (by users) forms.
• When a form submission is received, often this gets processed (e.g. contact form) by a team or ‘actioned’, at this point the submission can be deleted but this means it is gone forever.
• The problem is that it would be good to have an ‘archive’ (or similar) where form submissions can be hidden by default but then still accessed if really needed for historic records.
• This would help when looking through a large set of responses to find things that ‘need action’.

Describe the solution you’d like

• AbstractFormSubmission would have a new date field archived_on
• AbstractFormSubmission would have a new user field archived_by
• By default, new form submissions would have set the archived_on archived_by fields to None
• By default, the form submission listing would not show archived, nor would archived form submissions be exported
• The form submission listing would have a button ‘show archived’ at the top, very similar to the ‘show disabled’ in the workflows listing, when clicked the view will change (new URL param) and archived submissions would show, plus there
• The form submission listing would have a button ‘archive’ that shows when a form submission is selected.
• AbstractFormPage should have a class method / attribute of disable_ability_to_archive or similar (default being False), if this is True the functionality of showing archived submission (including ability to archive) should be hidden from the user. It is possible the name / default could be reversed so that only opt-in is used for this new feature. This also avoids another ‘setting’ added for this.
• When showing archived listings, there should be a way to un-archive a form response, this option should appear when an archived response is checked.
• There should be a class method on AbstractFormSubmission OR AbstractFormPageto do this change on the submission, this helps when wanting to customise the behaviour (trigger an email for example) of when something is archived or un-archived.

Reference - workflows with show disabled button

Describe alternatives you’ve considered

• This can be built with a customisation without too many issues, migrating lots of existing form pages to this would be a bit complex as changed models may be needed though.
• Archive may not be the best approach, maybe a starred type field or flagged would be more suitable, with the ability for this to be defaulted (although, this creates a more complex set of interactions to consider).

Additional context

These three form builder solutions do NOT provide this functionality, which may indicate that it is not useful

• JotForms allows deletion but not ‘archive’ https://www.jotform.com/answers/1717595-how-can-i-archive-old-form-responses
• Google allows deletion but not ‘archive’ https://support.google.com/docs/answer/2917686?hl=en#zippy=%2Cdelete-individual-responses
• Typeform does not allow undelete https://www.typeform.com/help/a/what-happens-to-deleted-results-typeforms-and-accounts-360040196472/

[lb-]

It may even be worthwhile doing a first round PR that has the underlying archive functionality of restrictions to the default listing, adds the fields to abstract form page, adds a new method to archive / un-archive.

Unit tests and functionality for that will be heaps and will be useful.

Then add the UI buttons as a seperate PR

[vibhuti019]

I am working on this one