help Whatsapp interface implementation

[alknopfler]

Main feature required:

• Interface implementation of whatsapp in order to send notifications using the whatsapp business api call.

• The implementation must follow the same format of the two parent interface methods:

  • parseTemplate(...)
  • SendMessage (...)

• Test must be covered

• Multi-recipient must be covered getting the same scenario that recipient for SMS and EMAIL. See more about that in the documentation Readme

• Error handling following the same structure