Put the chicken breasts in a 6- to 8-quart slow cooker. Mix the cumin, coriander, oregano, paprika, red pepper flakes, salt and a few grinds of pepper in a small bowl. Sprinkle the spices over the chicken. Add the beans, green chiles, garlic and chicken broth to the slow cooker and stir it all around. Cover and cook on low until the chicken is cooked through and easy to shred, 7 to 8 hours. Remove the chicken to a medium bowl and shred with two forks. Combine the heavy cream and masa harina in a small bowl. Mix until smooth. Return the chicken to the slow cooker along with the masa mixture and corn. Cover and cook until the chili is thickened and the corn is warmed through, about 30 minutes. Ladle the chili into bowls and top with cheese and avocado. Serve with lime wedges.