It took just one TV movie to change young actor Zac Efron from a supporting player to a bonafide teen star. Of course, that TV movie was The Disney Channel’s tween pop cultural phenomenon, “High School Musical” (2005), which elevated Efron to major league heartthrob status for his eminently crushable turn as a high school jock who discovers his hidden love for singing. Prior to “High School Musical,” the Arroyo Grande, CA native had appeared in a string of supporting and minor roles on television, most notably in the WB teen drama “Summerland” (2004-05), which starred another reigning tween