Known issues with Vulkan rendering backend

• The rotation using mouse doesn't work about all axes
• RenderMaterial::DisplayMode::WIREFRAME_SURFACE is not supported yet
• Closing the render window using esc key is not supported yet
• Point rendering not supported yet

Not urgent

• Debug render mode is not fully supported (Nick will expand; also mention axis rendering)
• Displaying the text on the render window is not supported yet. So p doesn't work.
• Add upper-level documentation for setting up Vulkan for the first time
• Multiple examples cannot be run sequentially
• Do some comparison of frame rates and memory usage between vulkan and vtk backends
• Add support for Linux and Mac (MoltenVK is apparently open-source now, so Mac support could be a possibility)

Misc.

• Tetrahedral, hexahedral, line meshes, etc.: will be added to the Vulkan version
• Certain material properties: will be added overtime, but this is also related to the material editor a bit
• Interactor features: some of the interactor features aren't implemented yet
• Cubemaps: there isn't support for the traditional variety of cubemaps as implemented in VTK (see latest MR)