UI: change conference overlay for participant

CMakeLists.txt

data/light/ic_moderator.png

data/light/ic_moderator_audio_muted.png

data/light/ic_moderator_audio_unmuted.png

data/light/ic_moderator_hangup.png

data/light/ic_moderator_maximize.png

data/light/ic_moderator_minimize.png

data/light/ic_star.png

src/CurrentCallVC.mm

src/views/ConferenceOverlayView.h

src/views/ConferenceOverlayView.mm

src/views/CustomBackgroundView.h

src/views/CustomBackgroundView.mm