SPECIAL PREMIERE: Once again, TV proves, as Fred Allen once observed, that imitation is the sincerest form of television. Because Masked Singer was such an instant success for Fox, the competition noticed just as instantly. And ABC, which ushered in the whole celebrity-competition genre in the 1970s with its tacky Battle of the Network Stars celebrity “track meets,” revives the concept and adds a hidden costumed aspect. Which is brilliant, in a way, because this way, viewers have to wait until competitors are unmasked to discover they weren’t really such big names in the first place. This time, watch Peacock do the 50-yard-dash, and Bee do the high jump…