Color token roles in PrintMacroGraph

[PappasBrent]

• Add a feature for the macro graph printer to optionally print tokens in different colors based on their roles.
• Add a configuration macro, PRINT_ROLE_COLORS, to enable/disable this feature.
• Make several adjustments to the TokenRole enum class to make development of this feature and future features involving token roles easier:
  • Add an X-macro, ROLES, for performing metaprogramming actions to all TokenRole enumerators.
  • Use ROLES macro to define a global vector containing all TokenRole enumerators to make it possible to iterate all roles.
  • Use ROLES macro to define a function for stringifying TokenRole enumerators.