The direction was required when a database could read or write from/to a
write buffer. Now it is clear from the usage context of a write buffer
context which of the two applications is meant (databases read, routers
write) so the direction flag is no longer required.
Running a server is now using `influxdb_iox run MODE [args]`, e.g.
`influxdb_iox run query --server-id 1`. Another mode that will follow
soon is `router`.
The old syntax `influxdb_iox run [args]` (w/o the mode part) is still
supported but a deprecation note will be printed.
Marco Neumann
Paul Dix
Jacob Marble
Carol (Nichols || Goulding)