Use pulished date, instead of created date, for default node listings

Problem/Motivation

This is a follow up to #1838918: Add 'published' timestamp to nodes and is dependent on that patch being committed.

Listing articles by creation date doesn't account for articles which are held in draft form for a time while being readied for publication. The new published date is a more appropriate basis for sorting nodes in lists.

Proposed resolution

Change all default node lists, including the front page listing, to use the published date instead of the created date.

Remaining tasks

1. Commit the patch from #1838918: Add 'published' timestamp to nodes
2. Change the default node lists to sort by published date
3. Change the default Views to sort by published date
4. Change nodes to list actual published date, instead of created date, if author info is displayed
5. Review patch and commit!

User interface changes

When author info is displayed on a node, the publication date will be shown, instead of the changed date. Sorting of node listings will be altered accordingly.

API changes

None.

Related issues:

• #1838918: Add 'published' timestamp to nodes
• #1892762: Alter or remove "Authored on" field on the node edit form