hwc: HWC 2.0 implementation

Add HWCLayer, HWCCallbacks and implement HWC2 layer functionality.

Change-Id: Ic7764e72f4cae534e68764df4cf80eb3db982071
diff --git a/.gitignore b/.gitignore
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+CMakeLists.txt
+.idea/
+.editorconfig
+.clang-complete