Add support for generic list menu listeners

This adds enablers/visiblers: "List.EnableAnySelected" "List.EnableMultipleSelected" "List.EnableSingleSelected" "List.EnableCall" "List.EnableIsFriend" "List.EnableIsNotFriend" "List.EnableMute" "List.EnableOfferTeleport"
This adds click callbacks: "List.CopyUUIDs" "List.OfferTeleport" "List.Pay" "List.RemoveFriend" "List.RequestFriendship" "List.ShowProfile" "List.StartAdhocCall" "List.StartCall" "List.StartConference" "List.StartIM" "List.AbuseReport" "List.ParcelEject" "List.Freeze" "List.EstateBan" "List.EstateEject" "List.ToggleMute"

Exposes LLRegionInfoModel::sendEstateOwnerMessage to the public to avoid further duplicated code

indra/llui/llscrolllistctrl.cpp

@@ -1740,6 +1740,7 @@ BOOL LLScrollListCtrl::handleRightMouseDown(S32 x, S32 y, MASK mask)
 		if (col->mHeader && col->mHeader->getRect().pointInRect(x,y)) // Right clicking a column header shouldn't bring up a menu
 			return FALSE;
 	}
+	gFocusMgr.setKeyboardFocus(this); // Menu listeners rely on this
 	mPopupMenu->buildDrawLabels();
 	LLMenuGL::showPopup(this, mPopupMenu, x, y);
 	return TRUE;