Update /servers and /servers/{{ID}} to use data from the interfaces tables

[ocket8888]

I'm submitting a ...

• new feature / enhancement request

Description

The /servers endpoint (and /servers/{{ID}} which uses the same handler) need to be updated to utilize data from the new tables added by whatever PR resolves #4611.

This depends on #4611

Traffic Control components affected ...

• Documentation
• Traffic Ops
• Traffic Ops client (Go)

Acceptance Criteria

• /servers in API 1.x and 2.x:
  • Uses the tables to provide the right legacy output for the GET method (should be unchanged)
  • Properly translates its legacy input into data for the new tables for the POST method (behavior should be unchanged)
  • Properly translates its legacy input into data for the new tables for the PUT method (behavior should be unchanged)
• /servers in API 3.x:
  • Provides the proper representations of cache servers as outlined in the blueprint for the GET method
  • Properly validates input to the POST and PUT methods, according to the rules laid out in the blueprint
  • New behavior adheres to the API guidelines (where applicable)
  • All behavior changes have been documented
• CDN-in-a-Box automated data insertion has been updated to use the new format (probably just need to edit a JSON template)
• The Traffic Ops Go client has been updated (v3 only) to return the new structures
  • Any associated unit and/or client/API integration tests have been updated to
    test the new structure and all pass.

See the Additional Server Interfaces blueprint for details.