drm_hwcomposer: Reorganize struct DrmHwcLayer

1. Move BlendMode, ColorSpace, SampleRange fields to the struct BufferInfo,
   allowing extraction of the data from native_handle using Metadata@4 API.
   Use it when data from HWC2 API can't be used (Currently it's a BlendMode
   case for CLIENT layer)

2. Rename DrmHwcLayer to LayerData and move it to compositor/ directory.
   (I was confused in the past because of similarity of names DrmHwcLayer
    vs HwcLayer, so this step should meke it easier for newcomers to
    understand the code)

3. Allow clonning of the LayerData to propagate it through the composition
   pipeline. Thus LayerData can be used by both HwcLayer to track state
   and by the compositor.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
2 jobs for internal-structures-rework in 10 minutes and 10 seconds