Changes to List counterparties

added the new arc-testnet enum value to the counterparties/items/invite/onchainNetwork response property for the response status 200

added the new arc-testnet enum value to the counterparties/items/rails/items/oneOf[subschema #2]/disabledNetworks/items response property for the response status 200

added the new arc-testnet enum value to the counterparties/items/rails/items/oneOf[subschema #2]/network response property for the response status 200

added the new arc-testnet enum value to the counterparties/items/rails/items/oneOf[subschema #2]/preferredNetwork response property for the response status 200

added the optional property counterparties/items/createdByAgent to the response with the 200 status

added the optional property counterparties/items/rails/items/oneOf[subschema #2]/disabledNetworks to the response with the 200 status

added the optional property counterparties/items/rails/items/oneOf[subschema #2]/preferredNetwork to the response with the 200 status

added the optional property counterparties/items/invite/onchainNetwork to the response with the 200 status