Improve the preview option view for the full content view mode when a media header is present

Problem/Motivation

The Varbase media header doesn't reflect on the preview

Steps to reproduce

1. Create a node that has Varbase media header
2. Choose media header
3. Preview the node

Proposed resolution

adding the following code when ever getParameter('node') is used

 if (empty($node)){
      $node = $this->routeMatch->getParameter('node_preview');
}

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ✅ Developer Documentation support on feature change/addition
  
  Changed for Varbase ~9.0.0
  Configuring Varbase Media Header
  Changed for Varbase ~10.0.0
  Configuring Varbase Media Header
• ✅ User Guide Documentation support on feature change/addition
• ✅ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-9.0.15, varbase_media_header-9.0.6, Varbase 10.0.0-beta1, varbase_media_header-10.0.0-alpha1

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

Tested in Varbase ~9.0.0

Test Basic page preview of the Full Content view mode - with Media Header

Test Basic page preview of the Teaser/Card view mode - with Media Header

Test Basic page - front-end view for the full content view mode - with Media Header

Test not saved yet new Basic page preview of the Full Content view - with Media Header

Test not saved yet new Basic page preview of the Teaser/Card view mode - with Media Header

Tested in Varbase ~10.0.0

Test Basic page preview of the Full Content view mode - with Media Header

Test Basic page preview of the Teaser/Card view mode - with Media Header

Test Basic page - front-end view for the full content view mode - with Media Header

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Issue #3373397 by Ahmad Khader: Improved the preview option view for the full content view mode when a media header is present