Add support for to only include a list of attributes in the output attribute

[LaurentLesle]

Add an optional attribute to list the paths to be exported in the output attribute.

resources impacted:

• restful_resource (resource)
• restful_resource (data)

If it sets to ["properties.loginServer", "properties.policies.quarantinePolicy.status"], it will set the following json to computed property output.

{
  "properties" : {
    "loginServer" : "registry1.azurecr.io"
    "policies" : {
      "quarantinePolicy" = {
        "status" = "disabled"
      }
    }
  }
}

Similar to https://registry.terraform.io/providers/Azure/azapi/0.1.0/docs/resources/azapi_resource#response_export_values