Set LangVersion to 11 (Azure#33862)

* Bump LangVersion

* Switch to fixed

Author: AlexanderSher

eng/Directory.Build.Common.props

@@ -27,7 +27,7 @@
 
   <!-- Setup default project properties -->
   <PropertyGroup>
-    <LangVersion>9</LangVersion>
+    <LangVersion>11</LangVersion>
     <!--
       Disable NU5105 NuGet Pack warning that the version is SemVer 2.0.
       SemVer 2.0 is supported by NuGet since 3.0.0 (July 2015) in some capacity, and fully since 3.5.0 (October 2016).

sdk/core/Azure.Core/src/RequestFailedException.cs

@@ -183,7 +183,8 @@ internal static (string FormattedError, string? ErrorCode, IDictionary<string, s
             foreach (HttpHeader responseHeader in response.Headers)
             {
                 string headerValue = response.Sanitizer.SanitizeHeader(responseHeader.Name, responseHeader.Value);
-                messageBuilder.AppendLine($"{responseHeader.Name}: {headerValue}");
+                string header = $"{responseHeader.Name}: {headerValue}";
+                messageBuilder.AppendLine(header);
             }
 
             var formatMessage = messageBuilder.ToString();

sdk/core/Azure.Core/src/ResourceIdentifier.cs

@@ -278,7 +278,7 @@ private static ResourceType ChooseResourceType(ReadOnlySpan<char> resourceTypeNa
             return "Invalid resource id.";
         }
 
-        private static ReadOnlySpan<char> PopNextWord(ref ReadOnlySpan<char> remaining)
+        private static ReadOnlySpan<char> PopNextWord(scoped ref ReadOnlySpan<char> remaining)
         {
             int index = remaining.IndexOf(Separator);
             if (index < 0)
@@ -350,14 +350,13 @@ private string ToResourceString()
             StringBuilder builder = new StringBuilder(initial);
             if (!IsProviderResource)
             {
-                builder.Append($"/{ResourceType.GetLastType()}");
+                builder.Append('/').Append(ResourceType.GetLastType());
                 if (!string.IsNullOrWhiteSpace(Name))
-                    builder.Append($"/{Name}");
+                    builder.Append('/').Append(Name);
             }
             else
             {
-                builder.Append(ProviderStart)
-                    .Append($"{ResourceType}/{Name}");
+                builder.Append(ProviderStart).Append(ResourceType).Append('/').Append(Name);
             }
 
             return builder.ToString();

sdk/core/Azure.Core/src/Shared/ClientDiagnostics.cs

@@ -190,7 +190,8 @@ internal static string CreateRequestFailedMessageWithContent(Response response,
             foreach (HttpHeader responseHeader in response.Headers)
             {
                 string headerValue = sanitizer.SanitizeHeader(responseHeader.Name, responseHeader.Value);
-                messageBuilder.AppendLine($"{responseHeader.Name}: {headerValue}");
+                string header = $"{responseHeader.Name}: {headerValue}";
+                messageBuilder.AppendLine(header);
             }
 
             return messageBuilder.ToString();