feat: support of multiple vshard groups

Summary

• Vshard related parameters moved from _pico_property as key-value to /_pico_tier as columns.
• Adopted changes from sbroad: multiple vshard routers, impl of changed traits (Vshard, Router)
• For BucketId target for plugin rpc added tier parameter

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• Depends on sbroad!464 (merged)
• Closes #784 (closed), #889 (closed)