Add "cbl-mariner-multi-package-reviewers" when a multi-package .spec file is added or removed (#8735)

Co-authored-by: Karim Eldegwy <karimeldegwy@microsoft.com>

.github/pull_request_template.md

@@ -17,6 +17,7 @@ Feel free to delete sections of the template which do not apply to your PR, or a
 - [ ] All source files have up-to-date hashes in the `*.signatures.json` files
 - [ ] `sudo make go-tidy-all` and `sudo make go-test-coverage` pass
 - [ ] Documentation has been updated to match any changes to the build system
+- [ ] If you are adding/removing a .spec file that has multiple-versions supported, please add [@microsoft/cbl-mariner-multi-package-reviewers](https://github.com/orgs/microsoft/teams/cbl-mariner-multi-package-reviewers) team as reviewer [(Eg. golang has 2 versions 1.18, 1.21+)](https://github.com/microsoft/azurelinux/tree/2.0/SPECS/golang)
 - [ ] Ready to merge
 
 ---

.pipelines/multi-package/MultiPackage.yml

@@ -0,0 +1,33 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+name: MultiPackage Check
+
+pr:
+  branches:
+    include:
+      - karimeldegwy/**
+
+variables:
+  - group: "Agent pools (DEV)"
+
+resources:
+  repositories:
+    - repository: CBL-Mariner-Pipelines
+      type: git
+      name: mariner/CBL-Mariner-Pipelines
+
+jobs:
+  - job: 'MultiPackageCheck'
+    pool:
+      type: linux
+      isCustom: true
+      name: "$(DEV_AMD64_Ubuntu_Managed)"
+    timeoutInMinutes: 15
+    displayName: 'Add reviewer if multi-package addition/removal detected'
+
+    steps:
+    - template: pipelines/multi-package/AddMultiPackTeamAsReviewer.yml@CBL-Mariner-Pipelines
+      parameters:
+        githubBaseRef: $(System.PullRequest.TargetBranch)
+        prID: $(System.PullRequest.PullRequestId)