Add DISPLAY_BT2020 ColorSpace and DataSpace

This already exists as an aidl dataspace, and some ICC profiles may
use this.

Bug: 349357636
Bug: 355264141
Flag: com.android.graphics.flags.display_bt2020_colorspace
Test: ColorSpaceTest
Change-Id: I6c4093264d41c6e4ca99a7d6569abfebda90ac3f