The shape is
SqlCredentials, which
the capability owns; this alias keeps the Hyperdrive-specific name callers
already import. Two things Hyperdrive adds to the general contract and that
the alias cannot express: the host is valid only inside the current Worker
instance, and the password is regenerated per instance rather than being a
long-lived secret. Neither may be cached beyond the request that read it.
Connection details for a Hyperdrive-backed database.