Add mac build env script

eng/restore-toolset.sh

@@ -15,6 +15,8 @@ function InitializeCustomSDKToolset {
   InstallDotNetSharedFramework "2.1.0"
   InstallDotNetSharedFramework "2.2.8"
   InstallDotNetSharedFramework "3.1.0"
+
+  CreateBuildEnvScript
 }
 
 # Installs additional shared frameworks for testing purposes
@@ -37,4 +39,22 @@ function InstallDotNetSharedFramework {
   fi
 }
 
+function CreateBuildEnvScript {
+  mkdir -p $artifacts_dir
+  scriptPath="$artifacts_dir/sdk-build-env.sh"
+  scriptContents="
+#!/bin/bash
+export DOTNET_SKIP_FIRST_TIME_EXPERIENCE=1
+export DOTNET_MULTILEVEL_LOOKUP=0
+
+export DOTNET_ROOT=$DOTNET_INSTALL_DIR
+export DOTNET_MSBUILD_SDK_RESOLVER_CLI_DIR=$DOTNET_INSTALL_DIR
+
+export PATH=$DOTNET_INSTALL_DIR:\$PATH
+export NUGET_PACKAGES=$NUGET_PACKAGES
+"
+
+  echo "$scriptContents" > ${scriptPath}
+}
+
 InitializeCustomSDKToolset