“What emerges from Cancino is that the power to award costs under rule 10 of the 2008 Rules (or rule 9 of the 2014 Rules) is to be exercised with significant restraint. In particular, the parties and their representatives must realise that these powers are of a fundamentally different character from the procedural provisions and practices found in the courts and some tribunals, whereby costs regularly “follow the event”; in other words, where a successful party will normally be awarded his or her costs.”