Problem/Motivation
When editing a node, the authoring information displays the user account name, the display name should be used instead.
Steps to reproduce
In an installation with some module that implements hook_user_format_name_alter implementation, like Real Name module, edit any existing node. The account name is always used as the author name in the node status information, even for users with a different display name.
Proposed resolution
Replace the current call to AccountInterface::getAccountName() by AccountInterface::getDisplayName() in NodeForm's meta information.
AccountInterface::getDisplayName() will also invoke hook_user_format_name_alter and then user name changes made by modules like "Real Name" will be visible in node edit form as well.
Remaining tasks
Review.
User interface changes
As described in description.