Use Configstore to test getWideColor function

Test: make tests in libs/gui/tests/
Test: adb sync
Test: adb shell /data/nativetest/libgui_test/libgui_test --gtest_filter="SurfaceTest.GetWideColorSupport"
Bug: 29940137

Change-Id: I618c300b1882d2ebd7474586d72f4d469e2d41bf