• NEW API: Renderer::renderStandaloneView() is a new method that can be used outside of
  beginFrame/endFrame on Views that have a RenderTarget associated. This can be used as a
  pseudo-compute API.
• Vulkan: bug fixes and improvements.
• engine: RenderTarget API can now use MRT.
• sample-gltf-viewer: improvements for reading zip files.
• sample-gltf-viewer: enable contact-shadows functionality in mobile gltf-viewer.
• windows: fix build error in filament_framegraph_test.