[Mobile]add knobs to set QUIC connection options and client connection options (#28883)

Commit Message: add knobs to set QUIC connection options and client connection options
Additional Description: This allows Envoy Mobile applications to set Quiche's connection options so that more performance tuning can be done.
Risk Level: Low
Testing: Unit tests
Docs Changes: n/a
Release Notes: n/a
Platform Specific Features: Mobile only

Signed-off-by: Renjie Tang <renjietang@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 450dd5bc89d7b8994c88614333328097128caeb1

envoy/config/core/v3/protocol.proto

@@ -56,7 +56,7 @@ message QuicKeepAliveSettings {
 }
 
 // QUIC protocol options which apply to both downstream and upstream connections.
-// [#next-free-field: 6]
+// [#next-free-field: 8]
 message QuicProtocolOptions {
   // Maximum number of streams that the client can negotiate per connection. 100
   // if not specified.
@@ -94,6 +94,12 @@ message QuicProtocolOptions {
   // Probes the peer at the configured interval to solicit traffic, i.e. ACK or PATH_RESPONSE, from the peer to push back connection idle timeout.
   // If absent, use the default keepalive behavior of which a client connection sends PINGs every 15s, and a server connection doesn't do anything.
   QuicKeepAliveSettings connection_keepalive = 5;
+
+  // An array of QUIC connection options represented in a serialized string, separated by commas.
+  string connection_options = 6;
+
+  // An array of QUIC client connection options represented in a serialized string, separated by commas.
+  string client_connection_options = 7;
 }
 
 message UpstreamHttpProtocolOptions {