Preferred option added to EHF file

EHF catalog files now support a preferred option, allowing items to be marked as High, Medium, Low or None (default). This helps highlight recommended items when multiple similar options are available. To use this feature, add "AdditionalItemProperty" to the item with the name exactly as "Preferred" and assign one of the supported values.

Note: The name must be exactly "Preferred" (case-sensitive), and valid values are: HIGH, MEDIUM, LOW  or NONE (all case-sensitive).