drm_hwcomposer: Rename DrmDisplayCompositor->DrmAtomicStateManager

Primary responsibilities of this class are:

1. Send composition/mode/active state over DRM atomic commit IOCTL
   to the kernel
2. Track commit state and keep planes owned by the Pipeline while they
   are either displayed or staged for displaying.
3. Keep framebuffers alive while they are in use or staged.

Not much related to composition itself, therefore rename it to
DrmAtomicStateManager and move it to drm folder.

Bump clang-tidy level of DrmAtomicStateManager.c to normal by fixing
minor clang-tidy findings.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
2 jobs for nonfunctional-cleanups-2022w06 in 14 minutes and 17 seconds (queued for 1 second)