Gov. Gretchen Whitmer isn't just a regular mom — she's a cool mom. She'll tell you herself. Or rather, her outfit will. She strides into the living room of her Lansing residence in all black, a rainbow lightning bolt off one shoulder, rainbow colors climbing each sleeve. The sweater was originally a gift from Whitmer to her gay daughter Sherry, who didn't want it. "My daughter laughs at me. I'm that mom who buys her the rainbow stuff and she's l…