External DNS provider update design and intent API

URL: /v2/project/{project-name}/rb/{rb-name}/{rb-version}/traffic-intent-sets/{traffic-intent-set-name}/dnsproviders
POST BODY:
{
  "name": "dnsprovider-intent-name1",    // use to label DNSendpointCRDs created
  "description": "dns provider intent for updating user facing microservice FQDNs to external DNS providers",
  "dnsProvider": [
    {
      "id": "microservice01", // unique name of the microservice - provides association to other connectivity intents
      "cluster-selector": "label1, label2, ...",  // labels to select which clusters this dns provider is to be used
      "externalDnsParameters": {   // list will be supplied to external-dns as parameters.
                                   // for example ...
        "aws-zone-type": "",          When using the AWS provider, filter for zones of this type (optional, options: public, private)
        "aws-zone-tags": "",          When using the AWS provider, filter for zones with these tags
        "aws-assume-role":"",         When using the AWS provider, assume this IAM role. Useful for hosted zones in another AWS account. Specify the full ARN, e.g. `arn:aws:iam::123455567:role/external-dns` (optional)
        "aws-batch-change-size":"1000",  When using the AWS provider, set the maximum number of changes that will be applied in each batch.
        "aws-batch-change-interval":"1s", When using the AWS provider, set the interval between batch changes.
        "aws-evaluate-target-health":"enabled", When using the AWS provider, set whether to evaluate the health of a DNS target (default: enabled, disable with --no-aws-evaluate-target-health)
        "aws-api-retries":"3",           When using the AWS provider, set the maximum number of retries for API calls before giving up.
        "aws-prefer-cname":"disabled"           When using the AWS provider, prefer using CNAME instead of ALIAS (default: disabled)
         etc.
      }
    },
    ...
  ]
}