The Nvidia Encoder now frees all resources when destroyed

res/dpr/utility/encode_color_conversion.frag

src/encoder/encoder.hpp

src/encoder/nvidia_encoder.cpp

src/encoder/nvidia_encoder.hpp

src/encoder/vulkan_encoder.cpp

src/encoder/vulkan_encoder.hpp

src/headset/emulated_headset.cpp

src/headset/remote_headset.cpp

src/vr_application.cpp