Remember when Ashley Judd used to make competent thrillers about scrappy, resourceful women in the late ‘90s? Fast forward one of those women to the present, hand her a Eurail pass, and give her an 18-year-old son who has been kidnapped and you’ve got “Missing,’’ which premieres tonight at 8 on channel 5. he twist here is that Judd’s character, Rebecca Winstone may be a PTA member in good standing, but she’s also a former CIA agent.