Redirect to the published URL when exiting preview

[kjac]

Prerequisites

• I have added steps to test this contribution in the description below

If there's an existing issue for this PR then this fixes #7922

Description

Following the discussion on #7922, when exiting document previews we should not blindly redirect to the "by ID" route. Instead we should:

1. Attempt to redirect to the published URL of the document being previewed, or
2. Redirect to the "by ID" route if permitted for published documents, or
3. Redirect to root if the "by ID" route is not permitted.

This PR implements that 👍

Testing this PR - with URL providers

When exiting preview for a given document, verify that:

1. If the document is already published, the client is redirected to the published URL of the document.
2. If the document is not published (draft-only), the client is redirected to the site root (in lieu of better options).

Test this both for culture variant and invariant content.

Testing this PR - without URL providers

Remove all URL providers with this code:

using Umbraco.Cms.Core.Composing;

namespace My.Site;

public class MyUrlProviderRemover : IComposer
{
    public void Compose(IUmbracoBuilder builder)
        => builder.UrlProviders().Clear();
}

When exiting preview for a given document, verify that:

1. With Umbraco:WebRouting:DisableFindContentByIdPath set to false, the client is redirected to the "by ID" route (as-is today).
2. With Umbraco:WebRouting:DisableFindContentByIdPath set to true, the client is redirected to the site root (in lieu of better options).

[AndyButland]

Looks logical to me and works as described 💪