SL-12475 add Inventory Favorites tab

indra/llui/llfolderview.h

indra/newview/app_settings/settings_per_account.xml

indra/newview/llinventorybridge.cpp

indra/newview/llinventorymodel.cpp

indra/newview/llinventorypanel.cpp

indra/newview/llinventorypanel.h

indra/newview/llpanelmaininventory.cpp

indra/newview/llpanelmaininventory.h

indra/newview/skins/default/xui/en/menu_inventory.xml

indra/newview/skins/default/xui/en/panel_main_inventory.xml

indra/newview/skins/default/xui/en/strings.xml