return errors from governor to client

Summary

• refactor: further simplify UpdateTopology operation

• test: increase log_crawler.wait_matched default timeout

• fix: don't send list of services in EnablePlugin operation

• fix: cleanup UpdateTopology governor step

• Simplify code
• Check plugin exists on client side

• refactor: simplify TopologyUpdateOp

• fix: cleanup EnablePlugin governor step even more

• Move all preconditions checking to the client
• Return errors if preconditions fail instead of silently ignoring them

• fix: return concrete error from InstallPlugin and UpdatePluginTopology

• fix: impl IntoBoxError::error_code for traft::Error

• fix: return concrete error from clusterwide ddl operations

• refactor: I be moving imports

• fix: return concrete error from EnablePlugin

• fix: used to panic when calling RaftStorage::entries with high=u64::MAX

• fix: used to return incorrect error in case plugin disappears during enable plugin operation

• refactor: preparations for returning errors from governor

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• Close #662 (closed)
• Cherry-pick to: none
• Docs follow-up: not necessary