ozone: scenic: Move ScenicSurface to a standalone class

In order to prepare to use ScenicSurface from multiple files, move it to
its own file.

Bug: 861853
Test: run_content_shell \
  --enable-features=VizDisplayCompositor,UseSkiaRenderer,UseSkiaDeferredDisplayList,UiGpuRasterization,OzoneDrmMojo
  --enable-oop-rasterization --enable-vulkan --enable-gpu-rasterization \
  --enable-raster-to-sk-image --use-raster-context-provider \
  --force-gpu-rasterization --use-gl=swiftshader --no-sandbox \
  --disable-gpu-sandbox

Change-Id: Ie1197b3f355a079513828353fc20e9a16162e9ea
Reviewed-on: https://chromium-review.googlesource.com/c/1362474
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616011}
4 files changed