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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