[4.2] Load the extension elements from the model in presets download

[laoneo]

Summary of Changes

The presets download view for the admin items, should load the extension elements from the model.

Testing Instructions

• Create a new administrator menu with the preset "Components Dashboard"
• Go to the menu items of this new menu, there should be only one with the name "Components"
• Click on it a couple of components to hide
  
• Save and close the menu item
• Go mack to the menu manager
• Click on export presets for the new menu
  

Actual result BEFORE applying this Pull Request

All Works.

Expected result AFTER applying this Pull Request

All works.

[pe7er]

I have tested this item ✅ successfully on 490dccf

The "Download as Preset" keeps working okay.
The XML exports of the Menu Item from before & after applying the PR, are identical.

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[toivo]

I have tested this item ✅ successfully on fc2fe3a

Tested successfully in Joomla 4.2.0-alpha3-dev of 3 May in Wampserver 3.2.8 using PHP 8.0.15

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[Quy]

RTC

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[roland-d]

Thanks everybody