demos: Add MacOS surface output to vulkaninfo

[jeremyk-lunarg]

Added output for a MacOSSurface in vulkaninfo and modified the CMake files to include the new files needed for this change:

metal_view.m Objective-C code to hook into Metal metal_view.h metal_view.m's header file

[shannon-lunarg]

I don't have a lot of Mac or Objective-C knowledge but from what I can tell this looks good to me.

With these changes, LVL and vulkaninfo still build and run on Linux and Windows.

[jeremyk-lunarg]

@mikes-lunarg: Changes made.

[jeremyk-lunarg]

@karl-lunarg: Updated