Network API: SIM Swap and Number Verification implementation

[superchilled]

This PR implements the Network Number Verification API and Network SIM Swap API into the Ruby SDK. Specifically it:

• Defines a new authentication class, NetworkAuthentication to provide an abstract interface for the specific OAuth flows used by the endpoints.
• Defines specific NetworkAuthentication::ClientAuthentication and NetworkAuthentication::ServerAuthentication classes to support client and server initiated OAuth flows.
• Updates the Namespace class to support these new authentication flows
• Updates other authentication classes to work in line with high-level authentication changes in the updated Namespace class
• Implements a NetworkNumberVerification class with the following methods:
  • verify
  • generate_oidc_uri
• Implements a NetworkSIMSwap class with the following methods:
  • check
  • retrieve_date
• Udpates the Client class to add accessors for NetworkNumberVerification and NetworkSIMSwap
• Adds unit, and some integration, tests for all of the above functionality.