Save code now email notification for submitter

        │14:39:31     +olasd | it's not going to be an easy thing to implement                                                             │
        │14:40:32     +olasd | (currently, in the backend, save code now looks "just like a regular origin update", and we have no         │
        │                    | provisions to hook into the completion of these events)                                                     │
        │14:41:04     +seirl | % mkdir swh-signals                                                                                         │
        │14:41:21   moranegg | to track when the origin was ingested?                                                                      │
        │14:41:30     +seirl | to know when to send the email                                                                              │
        │14:41:32     +olasd | to trigger the email notification, yeah                                                                     │
        │14:42:14     +olasd | (and ideally, you want the notification to trigger when the origin is visible on the read-only copy, so     │
        │                    | really you'd need to hook into postgresql replication *mindsplosion*)   

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Migrated from T1226 (view on Phabricator)