C#: Make WithDotNet public

Author: mbg

csharp/autobuilder/Semmle.Autobuild.CSharp/DotNetRule.cs

@@ -70,7 +70,16 @@ public BuildScript Analyse(IAutobuilder<CSharpAutobuildOptions> builder, bool au
                 });
         }
 
-        private static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builder, Func<string?, IDictionary<string, string>?, BuildScript> f)
+        /// <summary>
+        /// Returns a script that attempts to download relevant version(s) of the
+        /// .NET Core SDK, followed by running the script generated by <paramref name="f"/>.
+        ///
+        /// The arguments to <paramref name="f"/> are the path to the directory in which the
+        /// .NET Core SDK(s) were installed and any additional required environment
+        /// variables needed by the installed .NET Core (<code>null</code> when no variables
+        /// are needed).
+        /// </summary>
+        public static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builder, Func<string?, IDictionary<string, string>?, BuildScript> f)
         {
             var installDir = builder.Actions.PathCombine(builder.Options.RootDirectory, ".dotnet");
             var installScript = DownloadDotNet(builder, installDir);