fix: [ASSMT-476]: include Spinnaker credentialsInfo in the payload

[edgarulg]

When migrating Spinnaker pipelines into Harness, there are Spinnaker stages that uses accounts in Spinnaker but the configuration of the stage does not have the cloudProvider type behind the accountName.
To handle those cases, we are sending information about the credentials in Spinnaker in the payload to be able to determinate the cloudProvider type and migrate to the correct cloud provider.

The payload now looks like the following:

{
"credentials": [
    {
      "name": "aws-root",
      "type": "aws"
    }
  ],
  "pipelines": [
    ...pipeline definition
  ]
}

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