The fight over the legalization of marijuana in Massachusetts isn’t over. But one side has already gone home. Last November, a well-funded and well-organized coalition of advocates led by the national Marijuana Policy Project persuaded more than 1.7 million Massachusetts voters to approve Question 4 and establish a system of regulated cannabis commerce. Since then, though, a new front has opened over legalized marijuana — dozens of fronts, actually, in cities and towns across the state, where voters and local officials have already imposed moratoriums and bans on licensed pot firms or are set to vote on similar measures this fall.