[Feat] Client-go which is used to communicate with the managed-clusters can be configed with qps and burst

[oeular]

[oeular]

At the best, the configuration can be different for the managed clusters.

[yue9944882]

@oeular sgtm, one feasible approach is to add the client-side rate-limit configurations under the spec of ClusterGateway (extending secrets via annotations). also, this feature should be gated according to its maturity. /cc @Somefive

[oeular]

If the feature is not assigned, we want to join next month.

[Somefive]

This feature looks good to me. It's okay for @oeular to start.