Tara theatre, London A young, gay Indian man learns steps to Britishness from a phantom vision of the Tory politician, but the result is less sinister a satire than it should be Remember Theresa May and her 2016 "citizen" speech ("If you believe you are a citizen of the world, you are a citizen of nowhere") at the height of her suspicious policies on immigration? Well, here she is back in her former pomp as home sec…