[ms-gltf] Add new port

[luncliff]

Changes

New port for https://github.com/microsoft/glTF-SDK in Windows / MacOS platforms.

• Update externals version and use VcPkg in CI glTF-SDK#66 updated the library's dependent RapidJSON's version. So the code can be built with VcPkg now.
• The version-string will be updated when the new version is released. (== Next of r1.9.5.0)

What does your PR fix?

There was no port request for this.

Which triplets are supported/not supported? Have you updated the CI baseline?

Linux is not supported.
ci.baseline.txt will be updated soon.

Does your PR follow the maintainer guide?

Yes!

[PhoebeHui]

@luncliff, could you format the vcpkg.json file? See github.com/microsoft/vcpkg/blob/master/docs/maintainers/maintainer-guide.md#manifest for solution.

[luncliff]

@PhoebeHui, I was waiting for the next release of the library since last December but seems like it can take more than months... :(
The port's version is r1.9.5.0 but the ref commit is not. Can this be allowed? I'd like to hear opinions about it.

In microsoft/glTF-SDK#66, I update some build configurations and source code. Fortunately the project's TC passed, so I'd like to use the changes if possible.

[PhoebeHui]

@luncliff, I think it's fine, we already have the comments about the ref commit, we can update that with new release in future.

[PhoebeHui]

All features test passed with x64-windows.

[luncliff]

@PhoebeHui Appreciate the changes and testing. (Sadly, things didn't go well last week)

I added a small patch because of <filesystem> support in Mac OS (x64-osx triplets).
It basically adds 2 more changes.

• source: _LIBCPP_NO_EXPERIMENTAL_DEPRECATION_WARNING_FILESYSTEM when __APPLE__
  Like warning for std::experimental::filesystem in MS STL, headers in MacOS SDK reports the deprecation and it is considered error. The library is used only in samples so I placed a macro definition.
• cmake: CMAKE_OSX_DEPLOYMENT_TARGET to 10.15.
  This version allows use of std::filesystem::path.
  Normally it is fine with CMake configuration, but I found that ninja places the minimum osx version to 10.11.