feat(security): Handle service and user pre-auth headers

[byronantak]

• Create user service endpoint to allow for a fuzzy search based on service name
• Create custom PreAuthFilter which takes both user and service headers into consideration.
  • The precedence is for user headers if both are specified
• Create logic for disambiguate which users / services to use when multiple services match the results
  Summary: use exact service first, then any services which are ancestors to this service (if their users exist)
• If a service does not exist and attempts authenication, a Pager Duty incident is created