C#: Download dotnet-install.sh to the scratch dir

Author: tamasvajk

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

@@ -190,18 +190,20 @@ BuildScript GetInstall(string pwsh) =>
                     }
                     else
                     {
+                        var dotnetInstallPath = builder.Actions.PathCombine(FileUtils.GetTemporaryWorkingDirectory(builder.Actions.GetEnvironmentVariable, builder.Options.Language.UpperCaseName, out var _), ".dotnet", "dotnet-install.sh");
+
                         var downloadDotNetInstallSh = BuildScript.DownloadFile(
                             "https://dot.net/v1/dotnet-install.sh",
-                            "dotnet-install.sh",
+                            dotnetInstallPath,
                             e => builder.Log(Severity.Warning, $"Failed to download 'dotnet-install.sh': {e.Message}"));
 
                         var chmod = new CommandBuilder(builder.Actions).
                             RunCommand("chmod").
                             Argument("u+x").
-                            Argument("dotnet-install.sh");
+                            Argument(dotnetInstallPath);
 
                         var install = new CommandBuilder(builder.Actions).
-                            RunCommand("./dotnet-install.sh").
+                            RunCommand(dotnetInstallPath).
                             Argument("--channel").
                             Argument("release").
                             Argument("--version").
@@ -211,7 +213,7 @@ BuildScript GetInstall(string pwsh) =>
 
                         var removeScript = new CommandBuilder(builder.Actions).
                             RunCommand("rm").
-                            Argument("dotnet-install.sh");
+                            Argument(dotnetInstallPath);
 
                         return downloadDotNetInstallSh & chmod.Script & install.Script & BuildScript.Try(removeScript.Script);
                     }