Empty fields are not resolved automatically

Problem/Motivation

When creating an article and node fields are left empty, the current method for comparing the FieldItemList with->equals()
method does not detect that the change can be resolved automatically.

Steps to reproduce

1. Create a article node(node/1) with user 1
2. Add title: Lorem
3. Leave body field empty/untouched
4. Save node and reopen the edit form for later use
5. Edit node/1 with user 2
6. Edit title: Lorem Ipsum
7. Edit body: Lorem Ipsum
8. Save node
9. Activate user 1 node edit form and resave the ”old” node form in step 4.
10. User 1 should receive a conflict notice with Title and body field, even there is no conflict with body field value as user 1 has not edited the field.

Proposed resolution

Add additional checks to FieldComparatorDefault.php and DefaultConflictDiscovery.php when the local field value is has default value and autoresolve these conflicts.