After the news was released that Billy Gilmour had contracted Covid-19 and would miss Scotland's do-or-die collision with Croatia on Tuesday, the mood in the national could be summed up in one word.F ** k. In the space of a month, the Chelsea star had gone from unlimited and probably not appointed in the Euro 2020 squad to running the show against England at Wembley, and a safe start for one of the biggest matches that Scotland's men's national team has ever faced.After his rapid rise, it seemed written in the stars that…