Probably far more people have now seen Judi Dench as M—the intelligence chief who’s the boss of James Bond—than anything she’s done in Shakespeare.  With that unmistakably rich voice, she played royalty in “Mrs. Brown” and in “Shakespeare in Love.”  But it is in Shakespeare’s plays, onstage, that Dench made her home as an actor, performing nearly all the major female roles in a stage career of some 60 years.  It’s not just that the language is beautiful, she thinks; Shakespeare “understood about every single emotion that any of us might feel at any time.”  Dench has distilled that body of knowledge into a book called “Shakespeare: The Man Who Pays the Rent,”a collaboration with the actor Brendan O’Hea that delves into each role in each production she performed in.  Having trained as a stage designer, Dench decided to “have a go” at acting, and made her début at a young age as Ophelia at one of the most prestigious theatres in Britain.  She talks with David Remnick about what’s hard—and not hard—in performing Shakespeare, and why she considers M in James Bond just as challenging.