color management: introduce alpha mode and make it double buffered

Signed-off-by: Sebastian Wick <sebastian@sebastianwick.net>
2 jobs for color in 45 seconds (queued for 1 second)
Status Job ID Name Coverage
  Containers Build
passed #4469682
container_build

00:00:25

 
  Test
passed #4469683
test

00:00:19