VPN-6098: Create a 'mark-as-shipped' task for Shipit integration

This task makes a call to the Shipit API to update the release's status
to "shipped" once all other release tasks have successfully completed.

Issue: #8945

taskcluster/config.yml

@@ -105,6 +105,11 @@ workers:
             implementation: beetmover-import-from-gcs-to-artifact-registry
             os: scriptworker
             worker-type: 'mozillavpn-{level}-beetmover'
+        shipit:
+            provisioner: scriptworker-k8s
+            implementation: scriptworker-shipit
+            os: scriptworker
+            worker-type: 'mozillavpn-{level}-shipit'
         succeed:
             provisioner: built-in
             implementation: succeed
@@ -126,3 +131,6 @@ release-promotion:
         - fetch
         - toolchain
         - toolchain-openssl
+
+shipit:
+    scope-prefix: project:mozillavpn:releng:ship-it

taskcluster/kinds/mark-as-shipped/kind.yml

@@ -0,0 +1,29 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+---
+loader: taskgraph.loader.transform:loader
+
+transforms:
+    - taskgraph.transforms.from_deps
+    - mozillavpn_taskgraph.transforms.set_name
+    - mozilla_taskgraph.transforms.scriptworker.shipit.mark_as_shipped
+    - taskgraph.transforms.task
+
+kind-dependencies:
+    - beetmover-ship
+
+tasks:
+    mark-as-shipped:
+        worker-type: shipit
+        from-deps:
+            group-by:
+                attribute: shipping-phase
+            copy-attributes: true
+            unique-kinds: false
+            set-name: false
+        shipit-product:
+            by-build-type:
+                addons/opt: mozilla-vpn-addons
+                default: mozilla-vpn-client
+        run-on-tasks-for: [action]

taskcluster/mozillavpn_taskgraph/transforms/set_name.py

@@ -0,0 +1,20 @@
+from taskgraph.transforms.base import TransformSequence
+from taskgraph.util.dependencies import get_primary_dependency
+
+
+transforms = TransformSequence()
+
+
+@transforms.add
+def set_name(config, tasks):
+    for task in tasks:
+        if config.kind == "mark-as-shipped":
+            dep = get_primary_dependency(config, task)
+            assert dep
+
+            product = (
+                "addons" if dep.attributes["build-type"] == "addons/opt" else "client"
+            )
+            task["name"] = f"mark-as-shipped-{product}"
+
+        yield task