drm_hwcomposer: Move HwcLayer out of DrmHwcTwo class

... to reduce complexity of DrmHwcTwo.* files.

Bump-up tidy level of new files to NORMAL (fix function naming,
add NOLINT, etc.)

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/Android.bp b/Android.bp
index aae6436..0a05376 100644
--- a/Android.bp
+++ b/Android.bp
@@ -110,6 +110,7 @@
         "backend/BackendManager.cpp",
         "backend/BackendRCarDu.cpp",
 
+        "hwc2_device/HwcLayer.cpp",
         "hwc2_device/hwc2_device.cpp",
     ],
 }