Improved depth encoding of dual-layer reprojection strategy

...dual_layer_reprojection/dual_layer_reprojection_base.glsl

src/encoder/nvidia_encoder.cpp

src/headset/emulated_headset.cpp

src/headset/headset.hpp

src/headset/openvr_headset.cpp

src/headset/openxr_headset.cpp

src/headset/remote_headset.cpp

src/strategy/dual_layer_reprojection.cpp