stripeCompleteOnboard endpoint/tests

[rconjoe]

Tests here will require nock intercepting calls to stripe accounts api, telling our API that the account has the requested capabilities (card_payments and transfers as "active") then update the onboarded claim on the auth user.

[rconjoe]

Something to note here for later is that where we store 'onboarded' data for sellers is no longer in auth, but in the database.

When claims data is loaded in the frontend, this needs to be adjusted to look at the DB data instead of auth claims.