Welcome to the J.J. Starbuck guide at TV Tome. Dale Robertson, who seemed to have disappeared after Death Valley Days, shows up again with longhorns on his Cadillac as a billionaire businessman who just likes to help good folks, punish bad ones, and homilize in J. J. Starbuck (Tuesdays, 9 to 10 P.M., NBC), one of several entries from the tireless Stephen J. Cannell. It's been a long time since Tales of Wells Fargo and Death Valley Days, so long that Dale Robertson's predecessor, a certain Mr. Reagan, as host of the latter traded his white hats for the White House. And yet, some things never change, in the 20 years since he left series television, time has stood still for Dale Robertson. His "new" character still wears 10-gallon white hats, Roy Rogers jackets and string ties, talks with a Texas accent so thick it would make J.R. gag, and drives a '64 Lincoln Continental with steer horns on the hood and a horn that honks The Eyes of Texas. Did anybody mention the word