Bug 1925327 - Add telemetry for when add-on is installed r=android-re…

…viewers,gmalekpour,twhite

Differential Revision: https://phabricator.services.mozilla.com/D226033

mobile/android/fenix/app/metrics.yaml

@@ -1345,6 +1345,27 @@ onboarding:
     metadata:
       tags:
         - Onboarding
+  add_on_installed:
+    type: event
+    description: |
+      User installed an add-on from the onboarding card.
+    extra_keys:
+      add_on_id:
+        type: string
+        description: |
+          The id of add-on that was installed.
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1925327
+    data_reviews:
+      - https://phabricator.services.mozilla.com/D226033
+    data_sensitivity:
+      - interaction
+    notification_emails:
+      - [email protected]
+    expires: never
+    metadata:
+      tags:
+        - Onboarding
   set_to_default:
     type: event
     description: |