This default only made sense in the context of what was supported by
`zcash_client_sqlite`, and not in any other context. Unified address
requests no longer have their parts conditioned by what feature flags
are available; instead, if a request is constructed for which the
required key parts are not supported under a particular selection of
feature flags, address generation will raise a runtime error.
This was necessary as of `orchard 0.7`, but due to CI not checking with
the `orchard` feature flag at the time the crate was updated, CI did not
catch this.
This change makes it easier for third parties to make use of the Unified
key infrastructure without incurring a dependency upon the rest of the
`zcash_client_backend` interfaces.
Kris Nuttycombe
Jack Grigg
Andrew Arnott
Francisco Gindre