<codecvt>: Using codecvt_utf16 with wofstream results in malformed UTF16 output

Describe the bug
Newline translation that the CRT is doing on our behalf is transforming \n into \r\n, but this isn't being reflected to the codecvt facet.

Command-line test case
STL version (git commit or Visual Studio version): Visual Studio 2019 version 16.4

C:\Users\bion\Desktop>type test.cpp
#define _SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING
#include <assert.h>
#include <codecvt>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <sstream>
#include <string_view>

using namespace std::string_view_literals;

int main() {
  const auto target = std::filesystem::temp_directory_path() / "wide.dat"sv;
  std::cout << target << "\n" << std::flush;
  {
    std::wofstream wide(target);
    auto fac =
        new std::codecvt_utf16<wchar_t, 0x10ffff,
                               std::codecvt_mode(std::consume_header |
                                                 std::generate_header)>();
    std::locale uni16(wide.getloc(), fac);
    wide.imbue(uni16);
    wide << "Some text\n";
  }

  {
    std::string actual;
    {
      std::ifstream i(target, std::ios_base::in | std::ios_base::binary);
      std::stringstream s;
      s << i.rdbuf();
      actual = std::move(s).str();
    }
    assert(actual == "\xFE\xFF\0S\0o\0m\0e\0 \0t\0e\0x\0t\0\r\0\n"sv);
  }

  return 0;
}

C:\Users\bion\Desktop>cl /EHsc /W4 /WX /std:c++latest /nologo .\test.cpp
test.cpp

C:\Users\bion\Desktop>.\test.exe
"C:\\Users\\bion\\AppData\\Local\\Temp\\wide.dat"
Assertion failed: actual == "\xFE\xFF\0S\0o\0m\0e\0 \0t\0e\0x\0t\0\r\0\n"sv, file .\test.cpp, line 34

C:\Users\bion\Desktop>

Note the incorrect 0x0D 0x0A terminating the file:

This is a dual of Microsoft-internal VSO-208747 / AB#208747.

Start by compiling and running the supplied Visual Studio 2019 reproducer using wofstream, codecvt_utf16, and the Windows CRT newline handling. Compare the generated wide.dat bytes with the assertion's expected UTF-16 sequence, then trace where newline translation occurs relative to the codecvt facet. Done means the reproducer passes without the extra or malformed carriage-return bytes.