Add ColorSpace class

The ColorSpace class can be used to create an RGB color space from
either primaries/whitepoint or an RGB->XYZ matrix.

The primaries and whitepoint are in xyY space. A utility function
is provided to compute xyY coordinates from XYZ coordinats.

The class contains numerous functions to create common RGB color
spaces (sRGB, DCI-P3, etc.).

Test: colorspace_test
Bug: 29940137
Change-Id: Ifba8701377d058f5877176dabf4183e904a4cde0