EZP-29290: As an Editor, I want to have preconfigured "Author" section while creating the content

[konradoboza]

Question	Answer
JIRA issue	EZP-29290
Bug/Improvement	yes
Target version	master
BC breaks	no
Tests pass	yes
Doc needed	yes

JIRA excerpt:

Currently, in v2 there is no preconfigured author section (fields filled in with the name and e-mail of the currently logged user). It would be more convenient for the editors to have this fields set automatically while creating a new content. Also, prefilling section with the default data should be configurable at the Author FieldType level.

Depends on:

• EZP-29290: As an Editor, I want to have preconfigured "Author" section while creating the content ezpublish-kernel#2392
• EZP-29290: Author Field Type prefilled with empty value by default ezpublish-kernel#2417

TODO:

• Implement feature / fix a bug.
• Fix new code according to Coding Standards ($ composer fix-cs).
• Ask for Code Review.

[konradoboza]

I discovered some problems with saving content with an empty author, some rework here needed.

[konradoboza]

I applied changes according to ezsystems/ezpublish-kernel#2417 - default value should be empty to avoid BC break. Changing that also fixed an issue with saving a content with empty Author fields. Please re-review @mikadamczyk @ViniTou @andrerom. :)

[barbaragr]

I can't add Content Type:

1. Go to Admin/Content Types/Content and click (+) button
2. Fill Name, Identifier and Content name pattern
3. Click Add field definition - error 500 is thrown: Undefined class constant DEFAULT_VALUE_EMPTY