EXT-7747 FIXED Disable the "Add" item of wearable context menu when it's inappropriate.

The "Add" item of wearable context menu is now disabled if multiple clothes selected
or when you can't add more wearables of the given type (max number is worn).

Reviewed by Nyx at https://codereview.productengine.com/secondlife/r/595/

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branch : product-engine