Add Publish/Subscribe method of redis cache

[aidan-kwon]

Proposed changes

If a redis client publishes a message to a channel, other clients subscribing the channel at the publishing time receives the message.

Types of changes

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• Bugfix
• New feature or enhancement
• Others

Checklist

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• I have read the CONTRIBUTING GUIDELINES doc
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• Lint and unit tests pass locally with my changes ($ make test)
• I have added tests that prove my fix is effective or that my feature works
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• Any dependent changes have been merged and published in downstream modules

[KimKyungup]

Thanks. @aidan-kwon :)

[joowon-byun]

I have just a few questions :)