Use StringBuilder

src/EFCore.Design/Design/Internal/CSharpHelper.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
 using System.Collections;
 using System.Globalization;
 using System.Numerics;
@@ -329,15 +330,17 @@ public virtual string Namespace(params string[] name)
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     public virtual string Literal(string? value)
-        // do not use @"" syntax as in Migrations this can get indented at a newline and so add spaces to the literal
+        // do not output @"" syntax as in Migrations this can get indented at a newline and so add spaces to the literal
         => value is not null
-            ? "\"" +
-                value.Replace(@"\", @"\\")
-                    .Replace("\"", "\\\"")
-                    .Replace("\0", @"\0")
-                    .Replace("\n", @"\n")
-                    .Replace("\r", @"\r") +
-                "\""
+            ? new StringBuilder(value)
+                .Replace("\\", @"\\")
+                .Replace("\0", @"\0")
+                .Replace("\n", @"\n")
+                .Replace("\r", @"\r")
+                .Replace("\"", "\\\"")
+                .Insert(0, "\"")
+                .Append("\"")
+                .ToString()
             : "null";
 
     /// <summary>
@@ -368,11 +371,11 @@ public virtual string Literal(char value)
         => "\'"
             + value switch
             {
-                '\'' => @"\'",
                 '\\' => @"\\",
                 '\0' => @"\0",
                 '\n' => @"\n",
                 '\r' => @"\r",
+                '\'' => @"\'",
                 _ => value.ToString()
             }
             + "\'";