Add delete drafts form

[thomasiles]

Add a delete draft button to live forms with draft

Trello card: https://trello.com/c/tP5Fd96d/2610-add-the-ability-to-delete-a-draft-of-a-live-form-with-a-confirmation-page

This PR replaces #2280 which was reverted in #2288. I reverted it because it prevented live forms being deleted, which the end to end tests rely on, even if it's not exposed to users.

The end-to-end tests delete forms after creating them to keep things tidy.

They manipulate the URL of a live form to directly navigate to the delete form page. At this point the form is a live state. The pages for deleting a form don't have content for deleting live forms so the tests check for the draft content.

def delete_form
    if page.has_link?(form_name)
      click_link(form_name, match: :one)
      live_form_url = page.current_url
      delete_path = live_form_url.gsub("live", "delete")

      visit delete_path
      expect(page.find("h1")).to have_content 'Are you sure you want to delete this draft?'
      choose "Yes", visible: false
      click_button "Continue"

      expect(page.find(".govuk-notification-banner")).to have_content "The draft form, ‘#{form_name}’, has been deleted"
      if page.has_css?('.govuk-table')
        expect(page.find('.govuk-table')).not_to have_content form_name
      end
    end
  end

I think we need to tidy this up. I'm going to raise another card to tackle this as it might need input from design and content or prioritising.

This PR adds a single new commit compared to the previous one. This commit allows live forms to be deleted as before and adds a comment why. Other than than nothing has changed. I've checked locally and the end to end tests pass with this change.

This PR allows users to revert draft forms to their live state. It only extends the current delete button controller to use the RevertDraftService when deleting forms in the live_with_draft_state.

It does a small amount of clean up and refactoring first.

• Ensure that you consider the wider context.
• Does it work when run on your machine?
• Is it clear what the code is doing?
• Do the commit messages explain why the changes were made?
• Are there all the unit tests needed?
• Do the end to end tests need updating before these changes will pass?
• Has all relevant documentation been updated?

[DavidBiddle]

All looks good and I've tested it in the review environment 🎉

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

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