Work on task  EXT-6722 (Create modified inventory view for "my outfits" tab in top-level appearance sidebar)

Code improvements:
 * Moved Accordion tab + Flat list into separate xml.
 * Implemented dynamic creation of the accordion tab via xml

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/312/

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branch : product-engine