Move the wire protocol support into the public API

pkg/analysis_server/lib/src/plugin/server_plugin.dart

Index: pkg/analysis_server/lib/src/plugin/server_plugin.dart
diff --git a/pkg/analysis_server/lib/src/plugin/server_plugin.dart b/pkg/analysis_server/lib/src/plugin/server_plugin.dart
index 556a87a48047d64aa8cd95ce4c944d4c5d435271..5862b4a638da23c315c9854114e97f7746c47280 100644
--- a/pkg/analysis_server/lib/src/plugin/server_plugin.dart
+++ b/pkg/analysis_server/lib/src/plugin/server_plugin.dart
@@ -16,6 +16,7 @@ import 'package:analysis_server/plugin/edit/fix/fix.dart';
 import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
 import 'package:analysis_server/plugin/index/index.dart';
 import 'package:analysis_server/plugin/index/index_core.dart';
+import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
 import 'package:analysis_server/src/domain_completion.dart';
@@ -24,7 +25,6 @@ import 'package:analysis_server/src/domain_server.dart';
 import 'package:analysis_server/src/domains/analysis/navigation_dart.dart';
 import 'package:analysis_server/src/domains/analysis/occurrences_dart.dart';
 import 'package:analysis_server/src/edit/edit_domain.dart';
-import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart';
 import 'package:analysis_server/src/search/search_domain.dart';
 import 'package:analysis_server/src/services/correction/assist_internal.dart';