[lldb-vscode] fix logging

[wallace]

Summary

This applies the patch clayborg sent me for fixing logging, which didn't include incoming messages from VSCode.

[clayborg]

you might want to abandon this in favor of my patch: https://reviews.llvm.org/D74566

lldb/tools/lldb-vscode/VSCode.cpp

std::string VSCode::ReadJSON() {
   if (!llvm::to_integer(length_str, length))
     return json_str;
 
   if (!input.read_expected(log.get(), "\r\n"))
     return json_str;
 
   if (!input.read_full(log.get(), length, json_str))
     return json_str;
     
+  if (log) {
+    *log << "--> " << std::endl
+         << "Content-Length: " << length << "\r\n\r\n"
+         << json_str << std::endl;
+  }
+
   return json_str;
 }
 
 // "OutputEvent": {
 //   "allOf": [ { "$ref": "#/definitions/Event" }, {
 //     "type": "object",
 //     "description": "Event message for 'output' event type. The event
 //                     indicates that the target has produced some output.",