Fix TwilioNTS to return ice servers in same format as CoturnHMAC

[Askaholic]

The response for ice_servers doesn't fit the format that the client is expecting because of the implementation of CoturnHMAC.

• First server returned has no credentials
• urls field is not a list
• all servers are missing credentialType

See the example response here: https://www.twilio.com/docs/stun-turn?code-sample=code-generate-nts-token&code-language=Python&code-sdk-version=6.x

The TwilioNTS client should take the response from the twilio API and massage it into the same format as the CoturnHMAC.