[Communication] - PhoneNumbers & Sms - Addressing board review comments (Azure#19738)

* [Communication] - PhoneNumbers - Move models out of Models namespace and rename ISO to Iso

* Update the threeLetterISOCountryName parameter name to twoLetterIsoCountryName

* Add model factory for PhoneNumberSearchResult

* Update the model factory for sms

Author: RezaJooyandeh

sdk/communication/Azure.Communication.PhoneNumbers/CHANGELOG.md

@@ -6,6 +6,7 @@
 - Added protected constructor to PurchasePhoneNumbersOperation and ReleasePhoneNumberOperation for mocking.
 
 ### Breaking Changes
+- All models are moved from Azure.Communication.PhoneNumbers.Models namespace to Azure.Communication.PhoneNumbers.
 - AcquiredPhoneNumber class is renamed to PurchasedPhoneNumber.
 - PhoneNumbersClient methods renamed:
   - GetPhoneNumber -> GetPurchasedPhoneNumber.
@@ -15,15 +16,15 @@
 - PhoneNumbersModelFactory static method AcquiredPhoneNumber is renamed to PurchasedPhoneNumber.
 - PurchasePhoneNumbersOperation and ReleasePhoneNumberOperation extend Operation instead of Operation<Response>.
 - Removed PhoneNumberOperationStatus and PhoneNumberOperationType.
+- Renamed ISOCurrencySymbol property to IsoCurrencySymbol in PhoneNumberCost.
+- Renamed threeLetterISOCountryName parameter to twoLetterIsoCountryName in PhoneNumbersClient.StartSearchAvailablePhoneNumbers and PhoneNumbersClient.StartSearchAvailablePhoneNumbersAsync.
 
 ## 1.0.0-beta.5 (2021-03-09)
 
 ### Added
 - Added PhoneNumbersClient (originally was part of the Azure.Communication.Administration package).
 - Added support for Azure Active Directory Authentication.
 
-
-
 ### Breaking Changes
 - PhoneNumberAdministrationClient has been replaced with PhoneNumbersClient, which has the same functionality but different APIs. To learn more about how PhoneNumbersClient works, refer to the [README.md][read_me]
 

sdk/communication/Azure.Communication.PhoneNumbers/api/Azure.Communication.PhoneNumbers.netstandard2.0.cs

@@ -5,7 +5,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Text.Json;
-using Azure.Communication.PhoneNumbers.Models;
+using Azure.Communication.PhoneNumbers;
 using Azure.Core;
 
 namespace Azure.Core.Pipeline