Add multiline model proto

Author: khou22

exa/language_server_pb/language_server.proto

@@ -15,6 +15,12 @@ service LanguageServerService {
   rpc GetAuthToken(GetAuthTokenRequest) returns (GetAuthTokenResponse) {}
 }
 
+message MultilineConfig {
+  // Multiline model threshold. 0-1, higher = more single line, lower = more multiline,
+  // 0.0 = only_multiline, default is 0.5
+  float threshold = 1;
+}
+
 // Next ID: 9, Previous field: disable_cache.
 message GetCompletionsRequest {
   codeium_common_pb.Metadata metadata = 1 [(validate.rules).message.required = true];
@@ -24,6 +30,7 @@ message GetCompletionsRequest {
   ExperimentConfig experiment_config = 7;
 
   string model_name = 10;
+  MultilineConfig multiline_config = 13;
 }
 
 // Next ID: 5, Previous field: latency_info.