This cl implements the VK_MVK_macos_surface extension, which
adds the vkCreateMacOSSurfaceMVK function on MacOS.

According to the spec:
"The VK_MVK_macos_surface extension is an instance extension.
 It provides a mechanism to create a VkSurfaceKHR object
 (defined by the VK_KHR_surface extension) that refers to an
 NSView, the native surface type of macOS, which is
 underpinned by a CAMetalLayer, to support rendering to the
 surface using Apple’s Metal framework."

Bug b/137673628

Change-Id: Iacf7696b1d9e52d7349ea4efa01f0acdd09a6c8f
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/33848Reviewed-by: Hernan Liatis <hliatis@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>