REFAC: Remove vulkan references, glm and imgui

CMake/External/CMakeLists.txt

CMake/External/External_glm.cmake

CMake/External/External_imgui.cmake

CMake/Findimgui.cmake

CMake/iMSTKConfig.cmake.in

CMakeLists.txt

Source/Animation/Particles/imstkRenderParticleEmitter.h

Source/Geometry/Decal/imstkDecal.h

Source/Geometry/Decal/imstkDecalPool.cpp

Source/Geometry/Decal/imstkDecalPool.h

Source/Geometry/Particles/imstkRenderParticles.cpp

Source/Geometry/Particles/imstkRenderParticles.h

Source/Geometry/imstkGeometry.h

Source/MeshIO/CMakeLists.txt

Source/Rendering/CMakeLists.txt

Source/Rendering/GUIOverlay/CMakeLists.txt

Source/Rendering/GUIOverlay/imgui_impl_glfw.cpp

Source/Rendering/GUIOverlay/imgui_impl_glfw.h

Source/Rendering/GUIOverlay/imgui_impl_vulkan.cpp

Source/Rendering/GUIOverlay/imgui_impl_vulkan.h