Export installationToken as output variable to allow it be used in subsequesnt steps (#47445)

Co-authored-by: Chidozie Ononiwu <chononiw@microsoft.com>

Author: azure-sdk-automation[bot]

eng/common/pipelines/templates/steps/login-to-github.yml

@@ -8,6 +8,9 @@ parameters:
 - name: VariableNamePrefix
   type: string 
   default: GH_TOKEN
+- name: ExportAsOutputVariable
+  type: boolean 
+  default: false
 - name: ScriptDirectory
   default: eng/common/scripts
 
@@ -20,6 +23,6 @@ steps:
     scriptLocation: scriptPath
     scriptPath: ${{ parameters.ScriptDirectory }}/login-to-github.ps1
     arguments: >
-     -InstallationTokenOwners '${{ join(''',''', parameters.TokenOwners) }}'
-     -VariableNamePrefix '${{ parameters.VariableNamePrefix }}'
-     
+      -InstallationTokenOwners '${{ join(''',''', parameters.TokenOwners) }}'
+      -VariableNamePrefix '${{ parameters.VariableNamePrefix }}'
+      -ExportAsOutputVariable:$${{ parameters.ExportAsOutputVariable }}

eng/common/scripts/login-to-github.ps1

@@ -22,6 +22,10 @@
   Prefix for the exported variable name (default: GH_TOKEN).
   With a single owner, exports as GH_TOKEN. With multiple owners, exports as GH_TOKEN_<Owner>.
 
+.PARAMETER ExportAsOutputVariable
+  When set in Azure DevOps, also exports the variable as an output variable
+  (##vso[task.setvariable ...;isOutput=true]) for downstream jobs/stages.
+
 .OUTPUTS
   Sets environment variables in the current process and exports them to the CI system:
   - Azure DevOps: sets secret pipeline variables via ##vso logging commands
@@ -34,7 +38,8 @@ param(
   [string] $KeyName = "azure-sdk-automation",
   [string] $GitHubAppId = '1086291', # Azure SDK Automation App ID
   [string[]] $InstallationTokenOwners = @("Azure"),
-  [string] $VariableNamePrefix = "GH_TOKEN"
+  [string] $VariableNamePrefix = "GH_TOKEN",
+  [switch] $ExportAsOutputVariable
 )
 
 $ErrorActionPreference = 'Stop'
@@ -239,6 +244,11 @@ function Invoke-LoginToGitHub {
     if ($null -ne $env:SYSTEM_TEAMPROJECTID) {
       Write-Host "##vso[task.setvariable variable=$variableName;issecret=true]$installationToken"
       Write-Host "Azure DevOps variable '$variableName' has been set (secret)."
+
+      if ($ExportAsOutputVariable) {
+        Write-Host "##vso[task.setvariable variable=$variableName;issecret=true;isOutput=true]$installationToken"
+        Write-Host "Azure DevOps output variable '$variableName' has been set (secret)."
+      }
     }
 
     # GitHub Actions: mask the token and export to GITHUB_ENV