Whatever trophies the Oscar-nominated Three Billboards Outside Ebbing, Missouri comes away with next month, Martin McDonagh’s film about a grieving mother calling out police inaction by erecting three blood-orange, blame-giving billboards can take credit for at least some real-world impact: A form of protest. From Miami to London and beyond, activists have adopted the Three Billboards approach to, in one case, call out Florida Senator Marco Rubio for his money-taking from…