EXT-8329 FIXED Provided disabling 'Wear Item' button after item was worn.

Details:
1 Updated condition is item can be worn considering situation when item is copied in COF but is not worn.
2 Avoided code duplication in method LLOutfitsList::canWearSelected()

reviewed by Vadim Savchuk and Neal Orman at https://codereview.productengine.com/secondlife/r/785/

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branch : product-engine