EXT-7914 FIXED (Update context menu for worn clothing in the Edit Outfit panel)

- Removed the following menu items: Move Up a Layer, Move Down a Layer.
- Added 'Replace' menu item.
- Implemented method replaceWearable() - handler for the 'Replace' menu item.

Reviewed by Mike Antipov at https://codereview.productengine.com/secondlife/r/642/

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branch : product-engine