EXT-6710 WIP Prepare to implementation - "Give inventory" related...

EXT-6710 WIP Prepare to implementation - "Give inventory" related functionality was moved from the LLToolDragAndDrop to a separate class - LLGiveInventory.

To allow give several inventory items to several selected residents I need some functionality encapsulated in LLToolDragAndDrop class out of it.
No functionality should be changed.

LLToolDragAndDrop was updated to use new LLGiveInventory'methods instead of removed ones.

There were moved methods related to:
 - give inventory item
 - give inventory category
 - log into chat
Such functionality was moved:
 - is give acceptable
 - do inventory give operation
 - send give inventory request to server
 - process give inventory for protected items

QA Notes: Functionality related to give inventory via drag and drop should be re-tested closely.

Reviewed by Richard Nelson at https://codereview.productengine.com/secondlife/r/364/

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branch : product-engine