EXCLUSIVE: Dame Joan Collins has fire in her belly. After a career that has spanned 75 years from post-war Rank Organisation starlet to  Dynasty  diva, this self-described “jobbing actor” has a hunger, ambition and energy that thespians half her age, younger even, would envy. For the Cannes Film Festival, the legendary dame, who doesn’t care much for walking, is taking dancing lessons to enable her to glide with gusto into the Palais de Festival for the opening night gala on May 12. “I thought I want to just be able to get on the red carpet and not be a lump,” she tells Deadline in an exclusive interview. “I’ve never liked walking. Whenever I saw that the Queen or the Queen Mother were having walks, I thought, ‘How can they do that? How boring?’ The only time I want to walk is when I’m walking around Selfridges department store,” she declares.…