[windows] warmup Azure CLI (#8427)

* [windows] warmup Azure CLI

Improve Azure CLI first run timing.
Follow up: #8294

Co-authored-by: Jesse Houwing <jesse.houwing@gmail.com>

* expose AZURE_EXTENSION_DIR to image generation

* suppress az warmup output

* refresh PATH before warmup

---------

Co-authored-by: Jesse Houwing <jesse.houwing@gmail.com>

Author: ilia-shipitsin

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

@@ -3,13 +3,33 @@
 ##  Desc:  Install Azure CLI
 ################################################################################
 
-Write-Host "Install the latest Azure CLI release"
-$azCliUrl = "https://aka.ms/installazurecliwindowsx64"
-Install-Binary -Url $azCliUrl -Name "azure-cli.msi"
+Write-Host 'Install the latest Azure CLI release'
+
+$azureCliConfigPath = 'C:\azureCli'
+# Store azure-cli cache outside of the provisioning user's profile
+[Environment]::SetEnvironmentVariable('AZURE_CONFIG_DIR', $azureCliConfigPath, [System.EnvironmentVariableTarget]::Machine)
+# make variable to be available in the current session
+${env:AZURE_CONFIG_DIR} = $azureCliConfigPath
+
+$azCliUrl = 'https://aka.ms/installazurecliwindowsx64'
+Install-Binary -Url $azCliUrl -Name 'azure-cli.msi'
 
 $azureCliExtensionPath = Join-Path $Env:CommonProgramFiles 'AzureCliExtensionDirectory'
-$null = New-Item -ItemType "Directory" -Path $azureCliExtensionPath
+$null = New-Item -ItemType 'Directory' -Path $azureCliExtensionPath
+
+[Environment]::SetEnvironmentVariable('AZURE_EXTENSION_DIR', $azureCliExtensionPath, [System.EnvironmentVariableTarget]::Machine)
+# make variable to be available in the current session
+${env:AZURE_EXTENSION_DIR} = $azureCliExtensionPath
+
+# Warm-up Azure CLI
+
+Write-Host "Warmup 'az'"
 
-[Environment]::SetEnvironmentVariable("AZURE_EXTENSION_DIR", $azureCliExtensionPath, [System.EnvironmentVariableTarget]::Machine)
+$env:PATH = [Environment]::GetEnvironmentVariable('PATH', 'Machine')
+az --help | Out-Null
+if ($LASTEXITCODE -ne 0)
+{
+   throw "Command 'az --help' failed"
+}
 
-Invoke-PesterTests -TestFile "CLI.Tools" -TestName "Azure CLI"
+Invoke-PesterTests -TestFile 'CLI.Tools' -TestName 'Azure CLI'