Parse a block colour from a number or string, as provided in a block definition.
HSV hue value (0 to 360), #RRGGBB string, or a message reference string pointing to one of those two values.
An object containing the colour as a #RRGGBB string, and the hue if the input was an HSV hue value.
If the colour cannot be parsed.
Parse a block colour from a number or string, as provided in a block definition.