message: Add more specific error message if user attempts to use comments in json
diff: @@ -735,6 +735,10 @@ namespace vcpkg::Json
  return Value();
  }
  +#define VCPKG_JSON_NO_COMMENTS_MSG \
  + "\n vcpkg does not support c-style comments, however most objects allow $-prefixed fields to be used as " \
  + "comments."
  +
  Value parse_keyword() noexcept
  {
  char32_t current = cur();
  @@ -820,6 +824,10 @@ namespace vcpkg::Json
  return Value::array(std::move(arr));
  }
  }
  + else if (current == '/')
  + {
  + add_error("Unexpected character in middle of array" VCPKG_JSON_NO_COMMENTS_MSG);
  + }
  else
  {
  add_error("Unexpected character in middle of array");
  @@ -861,6 +869,11 @@ namespace vcpkg::Json
  add_error("Unexpected EOF; expected colon");
  return res;
  }
  + else if (current == '/')
  + {
  + add_error("Unexpected character; expected colon" VCPKG_JSON_NO_COMMENTS_MSG);
  + return res;
  + }
  else
  {
  add_error("Unexpected character; expected colon");
  @@ -917,6 +930,10 @@ namespace vcpkg::Json
  return Value();
  }
  }
  + else if (current == '/')
  + {
  + add_error("Unexpected character; expected comma or close brace" VCPKG_JSON_NO_COMMENTS_MSG);
  + }
  else
  {
  add_error("Unexpected character; expected comma or close brace");
  @@ -945,6 +962,11 @@ namespace vcpkg::Json
  case 'n':
  case 't':
  case 'f': return parse_keyword();
  + case '/':
  + {
  + add_error("Unexpected character; expected value" VCPKG_JSON_NO_COMMENTS_MSG);
  + return Value();
  + }
  default:
  if (is_number_start(current))
  {
  