feat(server): add CLIENT INFO command

[rafaelperoco]

Summary

• Add CLIENT INFO subcommand (Redis-compatible)
• Returns info about current connection (same format as CLIENT LIST)
• Add test in connection_test.py

Closes #4860

Supersedes #5597 (rebased on current main with updated API)

[Copilot]

Pull request overview

Adds support for the Redis-compatible CLIENT INFO subcommand on the server and verifies its behavior with a new integration test.

Changes:

• Implemented ClientInfo handler in ServerFamily::Client to return information about the current connection in the same format as CLIENT LIST.
• Extended CLIENT HELP output to document the new INFO subcommand.
• Added test_client_info in connection_test.py to validate the new command’s response shape and content.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/server/server_family.cc	Adds the ClientInfo helper, wires it into the CLIENT command dispatcher, and updates CLIENT HELP text to include the INFO subcommand.
tests/dragonfly/connection_test.py	Introduces test_client_info to ensure CLIENT INFO is accepted, returns a string for the current connection only, and matches the ID reported by CLIENT LIST.

[romange]

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