Add extensions and update SPIRV_Cross.
- Add support for extensions:
- VK_KHR_maintenance1;
- VK_KHR_shader_draw_parameters;
- VK_KHR_get_physical_device_properties2;
- VK_KHR_push_descriptor;
- Add ability to track and access supported and enabled extensions.
- Update to latest SPIRV-Cross version.