Create `cnpj-dv` (check digits)

[juliolmuller]

Create a new package cnpj-dv to calculate check digits (dígitos verificadores) for CNPJ. Although the logic of calculating these numbers are already implemented inside cnpj-gen, these should be removed from that in the next major version in favor of this package.

• Create a class CnpjCheckDigits to lazyly calculate first and second checkdigits. The base CNPJ for the calculation should be passed to the constructor and validated accordingly:
  • CNPJ provided should have between 12 and 14 digits after sanitization. Throw error if not met.
  • CNPJ should be provided as string, list of strings or list of integers.
• The package should support the new alphanumeric format for CNPJ (Create cnpj-dv (check digits) #25).
• All errors thrown by the package should be custom, prefixed with CnpjCheckDigits*TypeError for type errors and CnpjCheckDigits*Exception for other exceptions.