feat(STONEINTG-892): override snapshot git url

The source key in the snapshot also the git url as well as the
revision.

This is a small followup fix for #274.

Not sure if there's a preferred name for example github urls, but
feel free to tweak it as you like.

docs/modules/ROOT/pages/how-to-guides/testing_applications/proc_creating_override_snapshot.adoc

@@ -34,6 +34,7 @@ spec:
       containerImage: quay.io/redhat-user-workloads/ws-sample-tenant/application-sample/component-sample@sha256:0db0a473a6abf5c15c424ab07cfbd5c40c06622fe648d4fe6a6b6abc224a0d0c <3>
       source: <4>
         git:
+          url: https://github.com/sample-org/sample-repo
           revision: fa8b89274a61ef0f1c257b7a84c37aa2ec844109
 ----
 <1> The label `test.appstudio.openshift.io/type: override` that indicates this is an `override` snapshot.