Enable save code now of software source code archives for specific users

Currently, Save Code Now only allows to fetch code available from a VCS. The rationale behind this was to avoid the service being abused by random users.

Now that we have authentication and authorization in place, and that Software Heritage ambassadors are coming, we can relax this constraint, allowing specific users the ability to trigger "save code now" also for .tar, .zip, packages etc.

This should be a simple modification to the current interface (add the new origin types in the drop down menu, and adapt the logic).

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Migrated from T3213 (view on Phabricator)