Backup/Restore Managed Instance (#1428)

* Enabled backup to and restore from URL

* Created RPC, but when process tries to load Microsoft.Azure.Storage.Blob.dll, it crashes

* Added create shared access token

* Code refactor

* Minor changes

* Changed RPC path

* Moved createSas RPC to the newly created BlobService, fixed PR comments

* Added sas expiration date parameter to the RPC

* Added copyright headers

* Removed ConnectionInstance property from BlobService

* Removed unhelpful comment

* Removed unused using statements

* Changed copy/paste comments

* Disposable objects fix

* Small formatting fix

* Changed backup to/restore from url supported device types

* Added backup to url integration test

* Created restore integration test. Test are now getting azure blob params from env variables instead of file.

* Culture invariant epiration date param, fixed comment, and typo

* Updated headers

* PR comments fix

* Changed supported device type logic

* string localization fix

* String formatting fix

* build failure fix

* Typo

* Updated supported restore device types

test/Microsoft.SqlTools.ServiceLayer.Test.Common/Constants.cs

@@ -9,6 +9,12 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.Common
     {
         public const string SqlConectionSettingsEnvironmentVariable = "SettingsFileName";
 
+        public const string AzureStorageAccountKey = "AzureStorageAccountKey";
+
+        public const string AzureStorageAccountName = "AzureStorageAccountName";
+
+        public const string AzureBlobContainerUri = "AzureBlobContainerUri";
+
         /// <summary>
         /// Environment variable used to get the TSDATA source directory root.
         /// K2 is under it.