Break out the gladioli. Housewife megastar Dame Edna Everage has set a March 23 opening for her return to Broadway in “It’s All About Me.” Directed by Jerry Zaks, the new show will start previews March 6 at a Shubert theater to be announced. The show squeaks in one week ahead of the similarly titled “All About Me,” the upcoming Broadway engagement of popular singer and musician Michael Feinstein, opening March 30. Some are speculating that Edna and Mikey are actually going to do one show, together, or two shows at the same theatre. Does the flamboyance meter go that high?