Ingrid Bergman, one of the most iconic actresses of the golden age of Hollywood, wrote one letter in 1947 that changed her life — and the history of cinema — forever, RadarOnline.com has learned. At 12, Ingrid Bergman already knew what she wanted to be when she grew up. “Her diary starts, ‘I’m very glad my dad gave me this diary because I can keep a daily note — record of when I will become a very famous actress,’” her daughter Isabella Rossellini told Closer. A dreamy child who lost her parents at a young age, Ingrid earned a scholarship to the same Swedish drama school that Greta Garbo atten…