ratelimit: add support for data-plane-api proto (#3675)

ratelimit: added support for api/envoy/service/ratelimit/v2/rls.proto. Envoy can use either proto to send client requests to a ratelimit server with the use of the use_data_plane_proto boolean flag in the ratelimit configuration. Support for the legacy proto is deprecated and will be removed at the start of the 1.8.0 release cycle.

Signed-off-by: Jose Nino <jnino@lyft.com>

Mirrored from https://github.com/envoyproxy/envoy @ b0874e3ebd3bf79cec09aa4480f07da5f5630d07

envoy/config/ratelimit/v2/rls.proto

@@ -27,4 +27,20 @@ message RateLimitServiceConfig {
     // requests.
     envoy.api.v2.core.GrpcService grpc_service = 2;
   }
+
+  // Specifies if Envoy should use the data-plane-api client
+  // :repo:`api/envoy/service/ratelimit/v2/rls.proto` or the legacy 
+  // client :repo:`source/common/ratelimit/ratelimit.proto` when
+  // making requests to the rate limit service. 
+  //
+  // .. note::
+  //
+  //   The legacy client will be used by
+  //   default until the start of the 1.9.0 release cycle. At the start of the
+  //   1.9.0 release cycle this field will be removed and only the data-plane-api
+  //   proto will be supported. This means that your rate limit service needs to
+  //   have support for the data-plane-api proto by the start of the 1.9.0 release cycle.
+  //   Lyft's `reference implementation <https://github.com/lyft/ratelimit>`_
+  //   supports the data-plane-api version as of v1.1.0.
+  bool use_data_plane_proto = 3 [deprecated = true];
 }