Before this change we would silently replace an instance with current
grade not Online if a new instance with the same name wanted to join.
This was a mistake as it would allow a race condition when joining
several instances at once.

- Now we explicitly store the current & target vshard configuration in
  global storage

Transferred replication factor from Properties table to new Tier table

Instance and Replicaset belongs to tier via new field tier in _pico_instance and _pico_replicaset

New cli option init-cfg with path to configuration file in yaml format. For now contains only info about tiers.

Also fix some fresh clippy warnings

Yaroslav Dynnikov authored 2 years ago and Yaroslav Dynnikov committed 2 years ago

Also make `Default` trait implementation for `struct Instance` public.
Because keeping it private makes no sence for a public struct with
public fields.