Audio mixer GUI and more vectorisation

applications/gui2/src/modules/camera.cpp

applications/gui2/src/modules/camera.hpp

applications/gui2/src/views/camera.cpp

applications/gui2/src/widgets/soundctrl.cpp

applications/gui2/src/widgets/soundctrl.hpp

components/audio/include/ftl/audio/buffer.hpp

components/audio/include/ftl/audio/mixer.hpp

components/audio/src/speaker.cpp

components/audio/test/mixer_unit.cpp

components/streams/include/ftl/streams/feed.hpp

components/streams/include/ftl/streams/renderer.hpp

components/streams/src/baserender.hpp

components/streams/src/feed.cpp

components/streams/src/renderer.cpp

components/streams/src/renderers/openvr_render.cpp

components/streams/src/renderers/openvr_render.hpp

components/streams/src/renderers/screen_render.cpp

components/streams/src/renderers/screen_render.hpp