[Feature] Implement Rate Limit feature

[vankichi]

Is your feature request related to a problem? Please describe.:

We're concerned that a surge of client requests could overload the system. To maintain stability and performance, we propose implementing a rate limiter.

Describe the solution you'd like:

Implement the Rate Limit feature

Describe alternatives you've considered:

If the request rate exceeds a predefined threshold within a specific timeframe, return a ServiceUnavailable gRPC status.
Include a Retry-After header in the gRPC metadata to inform the client of the recommended retry delay.
Users are allowed to set rate limits in values.yaml.