When some of the same messages are redefined anywhere in a Go project,
the protobuf package panics (see
https://github.com/golang/protobuf/issues/178).
Since this package is internal, there is no way to work around it, as
one cannot use it directly, but also cannot define the same messages.
There is no downside in making the package accessible.
When opening the wallet, ask for passphrase as well as for the PIN
and return the relevant error (PIN/passphrase required). Open must then
be called again with either PIN or passphrase to advance the process.
This also updates the console bridge to support passphrase authentication.
