Function getAuthenticatorFromEnvironment

getAuthenticatorFromEnvironment(__namedParameters): Authenticator
Look for external configuration of authenticator.

Try to get authenticator from external sources, with the following priority:
1. Credentials file (ibm-credentials.env)
2. Environment variables
3. VCAP Services (Cloud Foundry)
Parameters
- __namedParameters: {
      httpsAgent?: Agent;
      requestToken?: (() => Promise<RequestTokenResponse>);
      serviceName: string;
      serviceUrl?: string;
  }
  - Optional httpsAgent?: Agent
  - Optional requestToken?: (() => Promise<RequestTokenResponse>)
    - (): Promise<RequestTokenResponse>
      Returns Promise<RequestTokenResponse>
  - serviceName: string
  - Optional serviceUrl?: string
Returns Authenticator
- Defined in authentication/utils/get-authenticator-from-environment.ts:48