The highlight of Monday’s Best of Broadway 2012-’13 season announcement event had to be seeing in person some of the actors from “Jersey Boys.” “Jersey Boys,” which tells the story of Frankie Valli and the Four Seasons, is the much-lauded, much-beloved musical sensation coming to town for a three-week run in October. Flying in for the announcement at the INB Performing Arts Center were Colin Trahan, who understudies seven roles in the touring production, Alayna Gallo, one of three actresses sharing more than 50 female roles in the play – she has 17 costume changes – and John Michael Dias, who plays Valli.