PHP Error when processing collaboration tags with disabled rich text editor

Problem/Motivation

When the rich text editor is disabled (e.g., due to insufficient user permissions), the system triggers an error while processing collaboration tags. This occurs because the `processWithTrackChangesData()` method is being called with `NULL` instead of an empty array as the second parameter, causing unexpected behavior in the document diff process.

Steps to reproduce

Have a content type with a CKEditor 5-enabled field 2. Create content with this field containing some text 3. Create a user with permissions to view but not edit the content 4. Log in as this user and view the content 5. The error occurs during the document diff processing when the editor is in read-only state

Proposed resolution

Modify the `DocumentDiffHelper::isRawDocumentChanged()` method to pass an empty array (`[]`) instead of `NULL` as the second parameter when calling `processWithTrackChangesData()`. This ensures proper handling of collaboration tags even when the editor is disabled.

Remaining tasks

1. Add test coverage for the scenario where the editor is disabled
2. Review and test the patch
3. Commit the fix
4. Update documentation if necessary

User interface changes

None. This is a backend fix that doesn't affect the user interface.

API changes

No API changes. This is a bug fix that maintains the existing API contract while correcting the parameter type passed to the

Data model changes

None. This fix doesn't affect the data model or storage structure.