feat(data_source): new dictionaries data source

[Integralist]

resource "fastly_service_vcl" "example" {
  name = "tf_example_service_for_dictionaries_data_source"
  domain {
    name = "%s.com"
  }
  dictionary {
    name       = "tf_example_1"
  }
  dictionary {
    name       = "tf_example_2"
  }
  dictionary {
    name       = "tf_example_3"
  }
  force_destroy = true
}

data "fastly_dictionaries" "example" {
  depends_on      = [fastly_service_vcl.example]
  service_id      = fastly_service_vcl.example.id
  service_version = fastly_service_vcl.example.active_version
}