add api server endpoint for manually qualifying a piece of freight

[krancour]

Depends on #1033

This would enable hotfixes without cluttering stage DAGs with subscriptions from prod (on the far right) to a warehouse (on the far left).

[rbreeze]

Explicitly adding 2 requirements for this endpoint so they aren't forgotten:

1. Verify stage exists
2. For Stage delete endpoint, remove the entry in approvedFor for that stage

[krancour]

For Stage delete endpoint, remove the entry in approvedFor for that stage

And verifiedIn while we're at it? 🙏