[Windows Binding] Incorrect string coding for sub-viewport window title in Multi-viewport mode

[JX-Master]

Version/Branch of Dear ImGui:

Version v1.66 WIP, Docking branch.

Back-end file/Renderer/OS: (or specify if you are using a custom engine back-end)

Back-ends: imgui_impl_d3d11.cpp + imgui_impl_win32.cpp
OS: Windows 10 (Simplified Chinese)
Compiler: MSVC 2017(v141)

My Issue/Question:

This is a very small issue that can be quickly fixed in no more than 5 minutes (I think :) ).

The problem is that when setting sub-window titles in multi-viewport mode in Windows,
the imgui binding program directly pass UTF-8 string to the system, where multi-byte characters is expected. This leads to incorrect title displaying when the input string is not ANSI C string.

The solution is inImGui_ImplWin32_SetWindowTitle funtion in imgui_impl_win32.cpp file, translate a UTF-8 string to UTF-16 wide char string and pass it to system by using ::SetWindowTextW(data->Hwnd, titlew); call. My solution would be like this:

static void ImGui_ImplWin32_SetWindowTitle(ImGuiViewport* viewport, const char* title)
{
	ImGuiViewportDataWin32* data = (ImGuiViewportDataWin32*)viewport->PlatformUserData;
	IM_ASSERT(data->Hwnd != 0);
	wchar_t titlew[260];
	UTF8ToUTF16(titlew, 260, title);   // Translate UTF-8 string to UTF-16
	::SetWindowTextW(data->Hwnd, titlew);  // And pass it to Windows.
}

Standalone, minimal, complete and verifiable example:

ImGui::Begin(u8"TTS测试");
// Some Stuff Here.
ImGui::End();

[ocornut]

Thank you @JX-Master, I have made a similar fix using Windows MultiByteToWideChar().
I have also confirmed that UTF-8 works as expected in the equivalent GLFW and SDL2 functions.