Provide ReactiveServerCommands for basic server interaction [DATAREDIS-659]

[spring-projects-issues]

Mark Paluch opened DATAREDIS-659 and commented

Provide a slim reactive server commands API to query the Redis version, issue ping commands, obtain database size, read/write config, retrieve connected clients and flush on server/db level.

Primairly required determining Redis details within a reactive environment

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Affects: 2.0 M3 (Kay)

Referenced from: pull request #253