Fix SYWEB-109 : No error if HS rejects the username in registration.
Fix SYWEB-109 : No error if HS rejects the username in registration.

Display all error messages from the server when registering, rather
than just the types of errors the client recognises.

TribeMedia/synapse,TribeMedia/synapse,illicitonion/synapse,TribeMedia/synapse,iot-factory/synapse,illicitonion/synapse,rzr/synapse,illicitonion/synapse,iot-factory/synapse,TribeMedia/synapse,rzr/synapse,howethomas/synapse,matrix-org/synapse,illicitonion/synapse,iot-factory/synapse,howethomas/synapse,howethomas/synapse,matrix-org/synapse,illicitonion/synapse,TribeMedia/synapse,matrix-org/synapse,rzr/synapse,iot-factory/synapse,rzr/synapse,howethomas/synapse,matrix-org/synapse,iot-factory/synapse,matrix-org/synapse,rzr/synapse,howethomas/synapse,matrix-org/synapse