AVONDALE, Ariz.—Before he headed onto the track for the biggest race of his career, Kyle Larson heard Mario Andretti praise him as one of the most well-rounded drivers in all of the motorsports. After Larson closed his 10-win season with his first Cup championship, the accolades continued, including one from his childhood hero. “Congratulations to the best race car driver I’ve ever seen,” Hall of Famer Tony Stewart wrote on Twitter. Comeback complete, Larson closed his second chance in NASCAR with his first championship Sunday with a title-winning victory at Phoenix Raceway. He was suspended nearly all of last season for using a racial slur, was fired by Chip Ganassi when all sponsors dropped Larson, and it took him until the end of the year to be reinstated to NASCAR and find a car owner willing to sign him. Stewart tried, very hard, but couldn’t get permission from the Stewart-Haas …