Add DeleteIfExistsAsync and CreateAsync container APIs (#6812)

Progress on #6766

Author: joelverhagen

src/NuGetGallery.Core/Services/CloudBlobContainerWrapper.cs

@@ -1,5 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
 using System.Threading.Tasks;
 using Microsoft.WindowsAzure.Storage.Blob;
 
@@ -37,5 +38,15 @@ public Task<bool> ExistsAsync()
         {
             return _blobContainer.ExistsAsync();
         }
+
+        public async Task<bool> DeleteIfExistsAsync()
+        {
+            return await _blobContainer.DeleteIfExistsAsync();
+        }
+
+        public async Task CreateAsync()
+        {
+            await _blobContainer.CreateAsync();
+        }
     }
 }

src/NuGetGallery.Core/Services/ICloudBlobContainer.cs

@@ -1,5 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
 using System.Threading.Tasks;
 using Microsoft.WindowsAzure.Storage.Blob;
 
@@ -11,5 +12,7 @@ public interface ICloudBlobContainer
         Task SetPermissionsAsync(BlobContainerPermissions permissions);
         ISimpleCloudBlob GetBlobReference(string blobAddressUri);
         Task<bool> ExistsAsync();
+        Task<bool> DeleteIfExistsAsync();
+        Task CreateAsync();
     }
 }