frontend/proto: Let CONNECTION_DATA not replace CONNECTION_ERROR.
frontend/proto: Let CONNECTION_DATA not replace CONNECTION_ERROR.

Instead, reserve some space for groups of status/state codes and then use a
new number / block for CONNECTION_DATA.

sysdb/sysdb,tokkee/sysdb,sysdb/sysdb,sysdb/sysdb,tokkee/sysdb,tokkee/sysdb