Switch provisioners to install Go from GitHub releases on Windows (#1026)

* add go to json toolset

* add install and validate go

* fiixing go tests

* fix validation for go

* check zero build version

* add 1.9 version

* setup variables for go

* fix comments

* remove script invokation

* remove lines

* fixing install go

* remove comments

* remove fake url

Co-authored-by: Dmitry Shibanov <v-dmshib@microsoft.com>

images/win/scripts/Installers/Install-Toolset.ps1

@@ -49,12 +49,34 @@ Function Set-DefaultPythonVersion {
     }
 }
 
+Function Set-DefaultGoVersion {
+    param(
+        [Parameter(Mandatory=$true)]
+        [object[]] $Toolset
+    )
+
+    $goToolset = $Toolset  | Where-Object { ($_.name -eq "go") -and ($_.default -ne "") } `
+                           | Select-Object default, arch -First 1
+
+    if ($goToolset.default -ne $null) {
+        $goPath = Join-Path $Env:AGENT_TOOLSDIRECTORY "/go/$($goToolset.default)/$($goToolset.arch)" -Resolve
+
+        Write-Host "Use Go $($goToolset.default) as a system Go"
+        Add-MachinePathItem -PathItem "$goPath\bin" | Out-Null
+        # Set the GOROOT environment variable.
+        setx GOROOT "$goPath" /M | Out-Null
+    } else {
+        Write-Host "Default Go version not found in toolset file!"
+    }
+}
+
 $ErrorActionPreference = "Stop"
 
 Import-Module -Name ImageHelpers -Force
 
 # Get toolcache content from toolset
-$ToolsToInstall = @("Python", "Node", "Boost")
+$ToolsToInstall = @("Python", "Node", "Boost", "Go")
+
 $tools = Get-ToolsetContent | Select-Object -ExpandProperty toolcache | Where {$ToolsToInstall -contains $_.Name}
 
 foreach ($tool in $tools) {
@@ -80,4 +102,5 @@ foreach ($tool in $tools) {
 }
 
 # Install default python version
-Set-DefaultPythonVersion -Toolset $tools
+Set-DefaultPythonVersion -Toolset $tools
+Set-DefaultGoVersion -Toolset $tools