Cleaner and more generic gRPC channel cache solution for filters that use Google gRPC on data plane

*Title*: *Cleaner and more generic gRPC channel cache solution for filters that use Google gRPC on data plane*

*Description*:
Currently Google gRPC channel used by filters are created for every request, which is not efficient and has high latency. We need to find a cleaner and more generic gRPC channel cache solution for filters that use Google gRPC on data plane.
We have short-term solution for ExtAuthz filter https://github.com/envoyproxy/envoy/pull/13265

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