Add the ability to turn off huffman for given http2 protocol option. (#42263)

Commit Message: Add the ability to selectively remove huffman encoding
headers as the sender for a given hop.
Additional Description: This is just
envoyproxy/envoy#38270 without the wonked git
history from being an old PR.
Risk Level: low (off by default)
Testing: Unit test, Running in Prod
Docs Changes: n/a
Release Notes: included
Platform Specific Features: n/a
Fixes: #38025

---------

Signed-off-by: Kevin Baichoo <[email protected]>

Mirrored from https://github.com/envoyproxy/envoy @ 5f2ccbd1bdc463a80d7184ba5d7c3eb659739fe7

Author: update-envoy[bot]

envoy/config/core/v3/protocol.proto

@@ -487,7 +487,7 @@ message KeepaliveSettings {
       [(validate.rules).duration = {gte {nanos: 1000000}}];
 }
 
-// [#next-free-field: 18]
+// [#next-free-field: 19]
 message Http2ProtocolOptions {
   option (udpa.annotations.versioning).previous_message_type =
       "envoy.api.v2.core.Http2ProtocolOptions";
@@ -678,6 +678,12 @@ message Http2ProtocolOptions {
 
   // Configure the maximum amount of metadata than can be handled per stream. Defaults to ``1 MB``.
   google.protobuf.UInt64Value max_metadata_size = 17;
+
+  // Controls whether to encode headers using huffman encoding.
+  // This can be useful in cases where the cpu spent encoding the headers isn't
+  // worth the network bandwidth saved e.g. for localhost.
+  // If unset, uses the data plane's default value.
+  google.protobuf.BoolValue enable_huffman_encoding = 18;
 }
 
 // [#not-implemented-hide:]